Raman Spectroscopy of Optically Trapped Single Biological Micro-Particles

Science.gov (United States)

Redding, Brandon; Schwab, Mark J.; Pan, Yong-le

2015-01-01

The combination of optical trapping with Raman spectroscopy provides a powerful method for the study, characterization, and identification of biological micro-particles. In essence, optical trapping helps to overcome the limitation imposed by the relative inefficiency of the Raman scattering process. This allows Raman spectroscopy to be applied to individual biological particles in air and in liquid, providing the potential for particle identification with high specificity, longitudinal studies of changes in particle composition, and characterization of the heterogeneity of individual particles in a population. In this review, we introduce the techniques used to integrate Raman spectroscopy with optical trapping in order to study individual biological particles in liquid and air. We then provide an overview of some of the most promising applications of this technique, highlighting the unique types of measurements enabled by the combination of Raman spectroscopy with optical trapping. Finally, we present a brief discussion of future research directions in the field. PMID:26247952

In-trap decay spectroscopy for {beta}{beta} decays

Energy Technology Data Exchange (ETDEWEB)

Brunner, Thomas

2011-01-18

The presented work describes the implementation of a new technique to measure electron-capture (EC) branching ratios (BRs) of intermediate nuclei in {beta}{beta} decays. This technique has been developed at TRIUMF in Vancouver, Canada. It facilitates one of TRIUMF's Ion Traps for Atomic and Nuclear science (TITAN), the Electron Beam Ion Trap (EBIT) that is used as a spectroscopy Penning trap. Radioactive ions, produced at the radioactive isotope facility ISAC, are injected and stored in the spectroscopy Penning trap while their decays are observed. A key feature of this technique is the use of a strong magnetic field, required for trapping. It radially confines electrons from {beta} decays along the trap axis while X-rays, following an EC, are emitted isotropically. This provides spatial separation of X-ray and {beta} detection with almost no {beta}-induced background at the X-ray detector, allowing weak EC branches to be measured. Furthermore, the combination of several traps allows one to isobarically clean the sample prior to the in-trap decay spectroscopy measurement. This technique has been developed to measure ECBRs of transition nuclei in {beta}{beta} decays. Detailed knowledge of these electron capture branches is crucial for a better understanding of the underlying nuclear physics in {beta}{beta} decays. These branches are typically of the order of 10{sup -5} and therefore difficult to measure. Conventional measurements suffer from isobaric contamination and a dominating {beta} background at theX-ray detector. Additionally, X-rays are attenuated by the material where the radioactive sample is implanted. To overcome these limitations, the technique of in-trap decay spectroscopy has been developed. In this work, the EBIT was connected to the TITAN beam line and has been commissioned. Using the developed beam diagnostics, ions were injected into the Penning trap and systematic studies on injection and storage optimization were performed. Furthermore, Ge

In-trap decay spectroscopy for ββ decays

International Nuclear Information System (INIS)

Brunner, Thomas

2011-01-01

The presented work describes the implementation of a new technique to measure electron-capture (EC) branching ratios (BRs) of intermediate nuclei in ββ decays. This technique has been developed at TRIUMF in Vancouver, Canada. It facilitates one of TRIUMF's Ion Traps for Atomic and Nuclear science (TITAN), the Electron Beam Ion Trap (EBIT) that is used as a spectroscopy Penning trap. Radioactive ions, produced at the radioactive isotope facility ISAC, are injected and stored in the spectroscopy Penning trap while their decays are observed. A key feature of this technique is the use of a strong magnetic field, required for trapping. It radially confines electrons from β decays along the trap axis while X-rays, following an EC, are emitted isotropically. This provides spatial separation of X-ray and β detection with almost no β-induced background at the X-ray detector, allowing weak EC branches to be measured. Furthermore, the combination of several traps allows one to isobarically clean the sample prior to the in-trap decay spectroscopy measurement. This technique has been developed to measure ECBRs of transition nuclei in ββ decays. Detailed knowledge of these electron capture branches is crucial for a better understanding of the underlying nuclear physics in ββ decays. These branches are typically of the order of 10 -5 and therefore difficult to measure. Conventional measurements suffer from isobaric contamination and a dominating β background at theX-ray detector. Additionally, X-rays are attenuated by the material where the radioactive sample is implanted. To overcome these limitations, the technique of in-trap decay spectroscopy has been developed. In this work, the EBIT was connected to the TITAN beam line and has been commissioned. Using the developed beam diagnostics, ions were injected into the Penning trap and systematic studies on injection and storage optimization were performed. Furthermore, Ge detectors, for the detection of X-rays, were

Influence of trap-assisted tunneling on trap-assisted tunneling current in double gate tunnel field-effect transistor

International Nuclear Information System (INIS)

Jiang Zhi; Zhuang Yi-Qi; Li Cong; Wang Ping; Liu Yu-Qi

2016-01-01

Trap-assisted tunneling (TAT) has attracted more and more attention, because it seriously affects the sub-threshold characteristic of tunnel field-effect transistor (TFET). In this paper, we assess subthreshold performance of double gate TFET (DG-TFET) through a band-to-band tunneling (BTBT) model, including phonon-assisted scattering and acoustic surface phonons scattering. Interface state density profile (D it ) and the trap level are included in the simulation to analyze their effects on TAT current and the mechanism of gate leakage current. (paper)

Precision tests of CPT invariance with single trapped antiprotons

Energy Technology Data Exchange (ETDEWEB)

Ulmer, Stefan [RIKEN, Ulmer Initiative Research Unit, Wako, Saitama (Japan); Collaboration: BASE-Collaboration

2015-07-01

The reason for the striking imbalance of matter and antimatter in our Universe has yet to be understood. This is the motivation and inspiration to conduct high precision experiments comparing the fundamental properties of matter and antimatter equivalents at lowest energies and with greatest precision. According to theory, the most sensitive tests of CPT invariance are measurements of antihydrogen ground-state hyperfine splitting as well as comparisons of proton and antiproton magnetic moments. Within the BASE collaboration we target the latter. By using a double Penning trap we performed very recently the first direct high precision measurement of the proton magnetic moment. The achieved fractional precision of 3.3 ppb improves the currently accepted literature value by a factor of 2.5. Application of the method to a single trapped antiproton will improve precision of the particles magnetic moment by more than a factor of 1000, thus providing one of the most stringent tests of CPT invariance. In my talk I report on the status and future perspectives of our efforts.

Influence of trap-assisted tunneling on trap-assisted tunneling current in double gate tunnel field-effect transistor

Science.gov (United States)

Zhi, Jiang; Yi-Qi, Zhuang; Cong, Li; Ping, Wang; Yu-Qi, Liu

2016-02-01

Trap-assisted tunneling (TAT) has attracted more and more attention, because it seriously affects the sub-threshold characteristic of tunnel field-effect transistor (TFET). In this paper, we assess subthreshold performance of double gate TFET (DG-TFET) through a band-to-band tunneling (BTBT) model, including phonon-assisted scattering and acoustic surface phonons scattering. Interface state density profile (Dit) and the trap level are included in the simulation to analyze their effects on TAT current and the mechanism of gate leakage current. Project supported by the National Natural Science Foundation of China (Grant Nos. 61574109 and 61204092).

Characterization of a magnetic trap by polarization dependent Zeeman spectroscopy

DEFF Research Database (Denmark)

Nielsen, Carsten Vandel; Lyngsøe, Jens Kristian; Thorseth, Anders

2008-01-01

This paper demonstrates a detailed experimental study of our cloverleaf magnetic trap for sodium atoms. By using polarization dependent Zeeman spectroscopy of our atomic beam, passing the magnetic trap region, we have determined important trap parameters such as gradients, their curvatures...

ATRAP - Progress Towards Trapped Antihydrogen

International Nuclear Information System (INIS)

Grzonka, D.; Goldenbaum, F.; Oelert, W.; Sefzick, T.; Zhang, Z.; Comeau, D.; Hessels, E.A.; Storry, C.H.; Gabrielse, G.; Larochelle, P.; Lesage, D.; Levitt, B.; Speck, A.; Haensch, T.W.; Pittner, H.; Walz, J.

2005-01-01

The ATRAP experiment at the CERN antiproton decelerator AD aims for a test of the CPT invariance by a high precision comparison of the 1s-2s transition in the hydrogen and the antihydrogen atom.Antihydrogen production is routinely operated at ATRAP and detailed studies have been performed in order to optimize the production efficiency of useful antihydrogen.For high precision measurements of atomic transitions cold antihydrogen in the ground state is required which must be trapped due to the low number of available antihydrogen atoms compared to the cold hydrogen beam used for hydrogen spectroscopy. To ensure a reasonable antihydrogen trapping efficiency a magnetic trap has to be superposed the nested Penning trap. First trapping tests of charged particles within a combined magnetic/Penning trap have started at ATRAP

ATRAP Progress Towards Trapped Antihydrogen

CERN Document Server

Grzonka, D; Gabrielse, G; Goldenbaum, F; Hänsch, T W; Hessels, E A; Larochelle, P; Le Sage, D; Levitt, B; Oelert, W; Pittner, H; Sefzick, T; Speck, A; Storry, C H; Walz, J; Zhang, Z

2005-01-01

The ATRAP experiment at the CERN antiproton decelerator AD aims for a test of the CPT invariance by a high precision comparison of the 1s‐2s transition in the hydrogen and the antihydrogen atom. Antihydrogen production is routinely operated at ATRAP and detailed studies have been performed in order to optimize the production efficiency of useful antihydrogen. For high precision measurements of atomic transitions cold antihydrogen in the ground state is required which must be trapped due to the low number of available antihydrogen atoms compared to the cold hydrogen beam used for hydrogen spectroscopy. To ensure a reasonable antihydrogen trapping efficiency a magnetic trap has to be superposed the nested Penning trap. First trapping tests of charged particles within a combined magnetic/Penning trap have started at ATRAP.

MATS and LaSpec: High-precision experiments using ion traps and lasers at FAIR

CERN Document Server

Rodriguez, D; Scheidenberger, C; Kreim, S; Gomez-Hornillos, M B; Aysto, J; Dickel, T; Geppert, C; Novikov, Y N; Tain, J L; Garcia-Ramos, J E; Bollen, G; Hobein, M; Audi, G; Beck, D; Winkler, M; Jesch, C; Vasiliev, A; Sanchez, R; Neidherr, D; Huber, G; Weber, C; Suhonen, M; Reinhard, P G; Jokinen, A; Lapierre, A; Bender, M; Martinez, T; Solders, A; Huyse, M; Matos, M; Szerypo, J; Seliverstov, M; Cortes, G; Cakirli, R B; Van Duppen, P; George, S; Block, M; Ahammed, M; Herfurth, F; Neyens, G; Habs, D; Thirolf, P G; Flanagan, K T; Roux, C; Schneider, D; Brodeur, M; Yordanov, D; Marx, G; Koudriavtsev, I; De, A; Boehm, C; Noertershaeuser, W; Blaum, K; Schabinger, B; Ettenauer, S; Plass, W R; Wendt, K; Nagy, S; Vorobjev, G; Minaya-Ramirez, E; Heenen, P-H; Quint, W; Kester, O; Le Blanc, F; Ray, A; Billowes, J; Kuehl, T; Kraemer, J; Lunney, D; Kolhinen, V; Rubio, B; Brunner, T; Nesterenko, D; Ferrer, R; Algora, A; Repp, J; Naimi, S; Eberhardt, K; Ziegler, F; Popov, A; Krieger, A; Campbell, P; Gartzke, E; Ketelaer, J; Heinz, S; Delheij, P; Ullrich, J; Dax, A; Crespo Lopez-Urrutia, J R; Eliseev, S; Das, P; Cano-Ott, D; Petrick, M; Moore, I; Litvinov, Y A; Schwarz, S; Dilling, J; Geissel, H; Bushaw, B A; Gusev, Y; Lallena, A M; Schweikhard, L; Schuch, R; Herlert, A

2010-01-01

Nuclear ground state properties including mass, charge radii, spins and moments can be determined by applying atomic physics techniques such as Penning-trap based mass spectrometry and laser spectroscopy. The MATS and LaSpec setups at the low-energy beamline at FAIR will allow us to extend the knowledge of these properties further into the region far from stability. The mass and its inherent connection with the nuclear binding energy is a fundamental property of a nuclide, a unique ``fingerprint{''}. Thus, precise mass values are important for a variety of applications, ranging from nuclear-structure studies like the investigation of shell closures and the onset of deformation, tests of nuclear mass models and mass formulas, to tests of the weak interaction and of the Standard Model. The required relative accuracy ranges from 10(-5) to below 10(-8) for radionuclides, which most often have half-lives well below 1 s. Substantial progress in Penning trap mass spectrometry has made this method a prime choice for ...

Plasmon assisted optical trapping: fundamentals and biomedical applications

Science.gov (United States)

Serafetinides, Alexandros A.; Makropoulou, Mersini; Tsigaridas, Georgios N.; Gousetis, Anastasios

2015-01-01

The field of optical trapping has dramatically grown due to implementation in various arenas including physics, biology, medicine and nanotechnology. Certainly, optical tweezers are an invaluable tool to manipulate a variation of particles, such as small dielectric spheres, cells, bacteria, chromosomes and even genes, by highly focused laser beams through microscope. As the main disadvantage of the conventional optical trapping systems is the diffraction limit of the incident light, plasmon assisted nanotrapping is reported as a suitable technique for trapping sub-wavelength metallic or dielectric particles. In this work, firstly, we report briefly on the basic theory of plasmon excitation, focusing on the interaction of nanoscale metallic structures with laser light. Secondly, experimental and numerical simulation results are also presented, demonstrating enhancement of the trapping efficiency of glass or SiO2 substrates, coated with Au and Ag nanostructures, with or without nanoparticles. The optical forces were calculated by measuring the particle's escape velocity calibration method. Finally, representative applications of plasmon assisted optical trapping are reviewed, from cancer therapeutics to fundamental biology and cell nanosurgery.

Cylindrical Penning traps with dynamic orthogonalized anharmonicity compensation for precision experiments

International Nuclear Information System (INIS)

Fei Xiang; Snow, W.M.

1999-01-01

Harmonic potentials can be produced in cylindrical ion traps by means of dynamic orthogonalized anharmonicity compensation with use of two (or multiple) sets of compensation electrodes. One special example is for traps with multiple identical electrodes which are not only easy to construct and allow access to the center region of the trap for particle loading and releasing, laser beams, and microwaves, but also flexible in forming harmonic potential wells in many locations. The nested trap configuration and the side-by-side trap configuration are readily available in this special scheme. Analytical solutions for cylindrical traps with multiple sets of compensation potentials are presented. This work will be useful for studies involving Penning trap diagnostics, atomic and molecular interactions (including the production of antihydrogen atoms), accurate mass measurements of exotic particles, and precision measurements of the spin precession frequencies of trapped particles

Cylindrical Penning traps with dynamic orthogonalized anharmonicity compensation for precision experiments

CERN Document Server

Fei Xiang

1999-01-01

Harmonic potentials can be produced in cylindrical ion traps by means of dynamic orthogonalized anharmonicity compensation with use of two (or multiple) sets of compensation electrodes. One special example is for traps with multiple identical electrodes which are not only easy to construct and allow access to the center region of the trap for particle loading and releasing, laser beams, and microwaves, but also flexible in forming harmonic potential wells in many locations. The nested trap configuration and the side-by-side trap configuration are readily available in this special scheme. Analytical solutions for cylindrical traps with multiple sets of compensation potentials are presented. This work will be useful for studies involving Penning trap diagnostics, atomic and molecular interactions (including the production of antihydrogen atoms), accurate mass measurements of exotic particles, and precision measurements of the spin precession frequencies of trapped particles.

Mass of 17O from Penning-trap mass spectrometry and molecular spectroscopy: A precision test of the Dunham-Watson model in carbon monoxide

International Nuclear Information System (INIS)

Mount, Brianna J.; Redshaw, Matthew; Myers, Edmund G.; Mueller, Holger S. P.

2010-01-01

By fitting the Dunham-Watson model to extensive rotational and vibrational spectroscopic data of isotopic variants of CO, and by using existing precise masses of 13 C, 16 O, and 18 O from Penning-trap mass spectrometry, we determine the atomic mass of 17 O to be M[ 17 O]=16.999 131 644(30) u, where the uncertainty is purely statistical. Using Penning-trap mass spectrometry, we have also directly determined the atomic mass of 17 O with the more precise result M[ 17 O]=16.999 131 756 6(9) u. The Dunham-Watson model applied to the molecular spectroscopic data hence predicts the mass of 17 O to better than 1 part in 10 8 .

Trap array configuration influences estimates and precision of black bear density and abundance.

Directory of Open Access Journals (Sweden)

Clay M Wilton

Full Text Available Spatial capture-recapture (SCR models have advanced our ability to estimate population density for wide ranging animals by explicitly incorporating individual movement. Though these models are more robust to various spatial sampling designs, few studies have empirically tested different large-scale trap configurations using SCR models. We investigated how extent of trap coverage and trap spacing affects precision and accuracy of SCR parameters, implementing models using the R package secr. We tested two trapping scenarios, one spatially extensive and one intensive, using black bear (Ursus americanus DNA data from hair snare arrays in south-central Missouri, USA. We also examined the influence that adding a second, lower barbed-wire strand to snares had on quantity and spatial distribution of detections. We simulated trapping data to test bias in density estimates of each configuration under a range of density and detection parameter values. Field data showed that using multiple arrays with intensive snare coverage produced more detections of more individuals than extensive coverage. Consequently, density and detection parameters were more precise for the intensive design. Density was estimated as 1.7 bears per 100 km2 and was 5.5 times greater than that under extensive sampling. Abundance was 279 (95% CI = 193-406 bears in the 16,812 km2 study area. Excluding detections from the lower strand resulted in the loss of 35 detections, 14 unique bears, and the largest recorded movement between snares. All simulations showed low bias for density under both configurations. Results demonstrated that in low density populations with non-uniform distribution of population density, optimizing the tradeoff among snare spacing, coverage, and sample size is of critical importance to estimating parameters with high precision and accuracy. With limited resources, allocating available traps to multiple arrays with intensive trap spacing increased the amount of

The construction of TRIGA-TRAP and direct high-precision Penning trap mass measurements on rare-earth elements and americium

Energy Technology Data Exchange (ETDEWEB)

Ketelaer, Jens

2010-06-14

The construction of TRIGA-TRAP and direct high-precision Penning trap mass measurements on rare-earth elements and americium: Nuclear masses are an important quantity to study nuclear structure since they reflect the sum of all nucleonic interactions. Many experimental possibilities exist to precisely measure masses, out of which the Penning trap is the tool to reach the highest precision. Moreover, absolute mass measurements can be performed using carbon, the atomic-mass standard, as a reference. The new double-Penning trap mass spectrometer TRIGA-TRAP has been installed and commissioned within this thesis work, which is the very first experimental setup of this kind located at a nuclear reactor. New technical developments have been carried out such as a reliable non-resonant laser ablation ion source for the production of carbon cluster ions and are still continued, like a non-destructive ion detection technique for single-ion measurements. Neutron-rich fission products will be available by the reactor that are important for nuclear astrophysics, especially the r-process. Prior to the on-line coupling to the reactor, TRIGA-TRAP already performed off-line mass measurements on stable and long-lived isotopes and will continue this program. The main focus within this thesis was on certain rare-earth nuclides in the well-established region of deformation around N {proportional_to} 90. Another field of interest are mass measurements on actinoids to test mass models and to provide direct links to the mass standard. Within this thesis, the mass of {sup 241}Am could be measured directly for the first time. (orig.)

The construction of TRIGA-TRAP and direct high-precision Penning trap mass measurements on rare-earth elements and americium

International Nuclear Information System (INIS)

Ketelaer, Jens

2010-01-01

The construction of TRIGA-TRAP and direct high-precision Penning trap mass measurements on rare-earth elements and americium: Nuclear masses are an important quantity to study nuclear structure since they reflect the sum of all nucleonic interactions. Many experimental possibilities exist to precisely measure masses, out of which the Penning trap is the tool to reach the highest precision. Moreover, absolute mass measurements can be performed using carbon, the atomic-mass standard, as a reference. The new double-Penning trap mass spectrometer TRIGA-TRAP has been installed and commissioned within this thesis work, which is the very first experimental setup of this kind located at a nuclear reactor. New technical developments have been carried out such as a reliable non-resonant laser ablation ion source for the production of carbon cluster ions and are still continued, like a non-destructive ion detection technique for single-ion measurements. Neutron-rich fission products will be available by the reactor that are important for nuclear astrophysics, especially the r-process. Prior to the on-line coupling to the reactor, TRIGA-TRAP already performed off-line mass measurements on stable and long-lived isotopes and will continue this program. The main focus within this thesis was on certain rare-earth nuclides in the well-established region of deformation around N ∝ 90. Another field of interest are mass measurements on actinoids to test mass models and to provide direct links to the mass standard. Within this thesis, the mass of 241 Am could be measured directly for the first time. (orig.)

Precision Measurement of the Electron's Electric Dipole Moment Using Trapped Molecular Ions

Science.gov (United States)

Cairncross, William B.; Gresh, Daniel N.; Grau, Matt; Cossel, Kevin C.; Roussy, Tanya S.; Ni, Yiqi; Zhou, Yan; Ye, Jun; Cornell, Eric A.

2017-10-01

We describe the first precision measurement of the electron's electric dipole moment (de) using trapped molecular ions, demonstrating the application of spin interrogation times over 700 ms to achieve high sensitivity and stringent rejection of systematic errors. Through electron spin resonance spectroscopy on 180Hf 19F+ in its metastable 3Δ1 electronic state, we obtain de=(0.9 ±7. 7stat±1. 7syst)×10-29 e cm , resulting in an upper bound of |de|<1.3 ×10-28 e cm (90% confidence). Our result provides independent confirmation of the current upper bound of |de|<9.4 ×10-29 e cm [J. Baron et al., New J. Phys. 19, 073029 (2017), 10.1088/1367-2630/aa708e], and offers the potential to improve on this limit in the near future.

Launch and capture of a single particle in a pulse-laser-assisted dual-beam fiber-optic trap

Science.gov (United States)

Fu, Zhenhai; She, Xuan; Li, Nan; Hu, Huizhu

2018-06-01

The rapid loading and manipulation of microspheres in optical trap is important for its applications in optomechanics and precision force sensing. We investigate the microsphere behavior under coaction of a dual-beam fiber-optic trap and a pulse laser beam, which reveals a launched microsphere can be effectively captured in a spatial region. A suitable order of pulse duration for launch is derived according to the calculated detachment energy threshold of pulse laser. Furthermore, we illustrate the effect of structural parameters on the launching process, including the spot size of pulse laser, the vertical displacement of beam waist and the initial position of microsphere. Our result will be instructive in the optimal design of the pulse-laser-assisted optical tweezers for controllable loading mechanism of optical trap.

Charged particle traps II applications

CERN Document Server

Werth, Günther; Major, Fouad G

2009-01-01

This, the second volume of Charged Particle Traps, is devoted to applications, complementing the first volume’s comprehensive treatment of the theory and practice of charged particle traps, their many variants and refinements. In recent years, applications of far reaching importance have emerged ranging from the ultra-precise mass determinations of elementary particles and their antiparticles and short-lived isotopes, to high-resolution Zeeman spectroscopy on multiply-charged ions, to microwave and optical spectroscopy, some involving "forbidden" transitions from metastable states of such high resolution that optical frequency standards are realized by locking lasers to them. Further the potential application of trapped ions to quantum computing is explored, based on the extraordinary quantum state coherence made possible by the particle isolation. Consideration is given to the Paul and Penning traps as potential quantum information processors.

Environment-assisted precision measurement

DEFF Research Database (Denmark)

Goldstein, G.; Cappellaro, P.; Maze, J. R.

2011-01-01

We describe a method to enhance the sensitivity of precision measurements that takes advantage of the environment of a quantum sensor to amplify the response of the sensor to weak external perturbations. An individual qubit is used to sense the dynamics of surrounding ancillary qubits, which...... are in turn affected by the external field to be measured. The resulting sensitivity enhancement is determined by the number of ancillas that are coupled strongly to the sensor qubit; it does not depend on the exact values of the coupling strengths and is resilient to many forms of decoherence. The method...... achieves nearly Heisenberg-limited precision measurement, using a novel class of entangled states. We discuss specific applications to improve clock sensitivity using trapped ions and magnetic sensing based on electronic spins in diamond...

Optical trapping and Raman spectroscopy of solid particles.

Science.gov (United States)

Rkiouak, L; Tang, M J; Camp, J C J; McGregor, J; Watson, I M; Cox, R A; Kalberer, M; Ward, A D; Pope, F D

2014-06-21

The heterogeneous interactions of gas molecules on solid particles are crucial in many areas of science, engineering and technology. Such interactions play a critical role in atmospheric chemistry and in heterogeneous catalysis, a key technology in the energy and chemical industries. Investigating heterogeneous interactions upon single levitated particles can provide significant insight into these important processes. Various methodologies exist for levitating micron sized particles including: optical, electrical and acoustic techniques. Prior to this study, the optical levitation of solid micron scale particles has proved difficult to achieve over timescales relevant to the above applications. In this work, a new vertically configured counter propagating dual beam optical trap was optimized to levitate a range of solid particles in air. Silica (SiO2), α-alumina (Al2O3), titania (TiO2) and polystyrene were stably trapped with a high trapping efficiency (Q = 0.42). The longest stable trapping experiment was conducted continuously for 24 hours, and there are no obvious constraints on trapping time beyond this period. Therefore, the methodology described in this paper should be of major benefit to various research communities. The strength of the new technique is demonstrated by the simultaneous levitation and spectroscopic interrogation of silica particles by Raman spectroscopy. In particular, the adsorption of water upon silica was investigated under controlled relative humidity environments. Furthermore, the collision and coagulation behaviour of silica particles with microdroplets of sulphuric acid was followed using both optical imaging and Raman spectroscopy.

Deceleration and Trapping of Heavy Diatomic Molecules for Precision Measurements

Science.gov (United States)

Berg, J. E. Van Den; Turkesteen, S. N. Hoekman; Prinsen, E. B.; Hoekstra, S.

2011-06-01

We are setting up a novel type of Stark-decelerator optimized for the deceleration and trapping of heavy diatomic molecules. Aim of these experiments is to prepare a trapped sample of ultracold molecules for precision studies of fundamental symmetries. The decelerator uses ring-shaped electrodes to create a moving trapping potential, a prototype of which has been shown to work for CO molecules. Molecules can be decelerated and trapped in the weak-field seeking part of excited rotational states. The alkaline-earth monohalide molecules (currently we focus on the SrF molecule) are prime candidates for next generation parity violation and electron-EDM studies. We plan to combine the Stark deceleration with molecular laser cooling to create a trapped sample of molecules at a final temperature of ˜ 200 μK. A. Osterwalder, S. A. Meek, G. Hammer, H. Haak and G. Meijer Phys. Rev. A 81 (51401), 2010. T. A. Isaev, S. Hoekstra, R. Berger Phys. Rev. A 82 (52521), 2010

Hole traps in n-GaN detected by minority carrier transient spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Tokuda, Yutaka; Yamada, Yujiro; Shibata, Tatsunari; Yamaguchi, Shintaro [Department of Electrical and Electronics Engineering, Aichi Institute of Technology, Yakusa, 470-0392 Toyota (Japan); Ueda, Hiroyuki; Uesugi, Tsutomu; Kachi, Tetsu [Toyota Central R and D Laboratories, Inc., Nagakute, 480-1192 Aichi (Japan)

2011-07-15

Minority carrier transient spectroscopy (MCTS) has been applied for the detection of hole traps in n-GaN using Schottky diodes. MCTS using 355 nm light emitting diodes is performed under isothermal conditions in the temperature range 280 to 330 K for n-GaN grown by metalorganic chemical vapor deposition on sapphire. Isothermal MCTS spectra reveal the E{sub v} + 0.86 eV hole trap with the trap concentration of 1.1x10{sup 16} cm{sup -3}. The E{sub v} + 0.86 eV hole trap has the higher concentration as compared to electron traps observed by deep level transient spectroscopy. Thus, the isothermal MCTS around room temperature provides a convenient way to evaluate the dominant trap in n-GaN. It is suggested that the E{sub v} + 0.86 eV hole trap is associated with the V{sub Ga}-related defect or carbon-related defect. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Positioning of the rf potential minimum line of a linear Paul trap with micrometer precision

DEFF Research Database (Denmark)

Herskind, Peter Fønss; Dantan, Aurélien; Albert, Magnus

2009-01-01

We demonstrate a general technique to achieve a precise radial displacement of the nodal line of the radiofrequency (rf) field in a linear Paul trap. The technique relies on the selective adjustment of the load capacitance of the trap electrodes, achieved through the addition of capacitors...... to the basic resonant rf circuit used to drive the trap. Displacements of up to ~100 µm with micrometer precision are measured using a combination of fluorescence images of ion Coulomb crystals and coherent coupling of such crystals to a mode of an optical cavity. The displacements are made without measurable...

Calorimetric Low-Temperature Detectors for X-Ray Spectroscopy on Trapped Highly-Charged Heavy Ions

Science.gov (United States)

Kilbourne, Caroline; Kraft-Bermuth, S.; Andrianov, V.; Bleile, A.; Echler, A.; Egelhof, P.; Ilieva, S.; Kilbourne, C.; McCammon, D.

2012-01-01

The application of Calorimetric Low-Temperature Detectors (CLTDs) has been proposed at the Heavy-Ion TRAP facility HITRAP which is currently being installed at the Helmholtz Research Center for Heavy Ion Research GSI. This cold ion trap setup will allow the investigation of X-rays from ions practically at rest, for which the excellent energy resolution of CLTDs can be used to its full advantage. However, the relatively low intensities at HITRAP demand larger solid angles and an optimized cryogenic setup. The influence of external magnetic fields has to be taken into account. CLTDs will also be a substantial part of the instrumental equipment at the future Facility for Antiproton and Heavy Ion Research (FAIR), for which a wide variety of high-precision X-ray spectroscopy experiments has been proposed. This contribution will give an overview on the chances and challenges for the application of CLTDs at HITRAP as well as perspectives for future experiments at the FAIR facility.

Winter School on Physics with Trapped Charged Particles - Abstracts and slides

International Nuclear Information System (INIS)

Pedersen, T.S.; Thompson, R.C.; Madsen, N.; Champenois, C.; Anderegg, F.; Fajans, J.; Knoop, M.; Scott Hangst, J.; Hilico, L.; Ulmer, S.; Blaum, K.; Drewsen, M.; Roos, C.; Schmidt, P.

2016-01-01

This winter school covered various topics of the physics of trapped charged particles. Lectures covered basic trap physics and recent developments in Penning traps, Paul traps..., collective behavior and non-neutral plasmas, as well as applications for fundamental physics, laser cooling, precision spectroscopy and quantum information. This document gathers a booklet of abstracts and the available slides of the presentations

Trap-assisted and Langevin-type recombination in organic light-emitting diodes

Science.gov (United States)

Wetzelaer, G. A. H.; Kuik, M.; Nicolai, H. T.; Blom, P. W. M.

2011-04-01

Trapping of charges is known to play an important role in the charge transport of organic semiconductors, but the role of traps in the recombination process has not been addressed. Here we show that the ideality factor of the current of organic light-emitting diodes (OLEDs) in the diffusion-dominated regime has a temperature-independent value of 2, which reveals that nonradiative trap-assisted recombination dominates the current. In contrast, the ideality factor of the light output approaches unity, demonstrating that luminance is governed by recombination of the bimolecular Langevin type. This apparent contradiction can be resolved by measuring the current and luminance ideality factor for a white-emitting polymer, where both free and trapped charge carriers recombine radiatively. With increasing bias voltage, Langevin recombination becomes dominant over trap-assisted recombination due to its stronger dependence on carrier density, leading to an enhancement in OLED efficiency.

PENTATRAP. A novel Penning-trap system for high-precision mass measurements

Energy Technology Data Exchange (ETDEWEB)

Doerr, Andreas

2015-01-21

The novel Penning-trap mass spectrometer PENTATRAP aims at mass-ratio determinations of medium-heavy to heavy ions with relative uncertainties below 10{sup -11}. From the mass ratios of certain ion species, the corresponding mass differences will be determined with sub-eV/c{sup 2} uncertainties. These mass differences are relevant for neutrino-mass experiments, a test of special relativity and tests of bound-state QED. Means to obtain the required precision are very stable trapping fields, the use of highly-charged ions produced by EBITs, a non-destructive cyclotron-frequency determination scheme employing detectors with single-ion sensitivity and a five-trap tower, that allows for measurement schemes being insensitive to magnetic field drifts. Within this thesis, part of the detection electronics was set up and tested under experimental conditions. A single-trap setup was realized. A Faraday cup in the trap tower enabled the proper adjustment of the settings of the beamline connecting the EBIT and the Penning-trap system, resulting in the first trapping of ions at PENTATRAP. A stabilization of switched voltages in the beamline and detailed studies of ion bunch characteristics allowed for reproducible loading of only a few ions. Detection of the axial oscillation of the trapped ions gave hints that in some cases, even single ions had been trapped. Furthermore, valuable conclusions about necessary modifications of the setup could be drawn.

Traps for antimatter and antihydrogen production

International Nuclear Information System (INIS)

Holzscheiter, M.H.

1994-01-01

Even though positrons have been captured and stored in ion traps for precision measurements, the recent trapping and cooling of antiprotons may be considered as the beginning of a new era in antimatter research. For the first time all the ingredients to produce the first atom of the antimatter world, the antihydrogen atom, are at hand, and several groups have entered an active discussion on the feasibility of producing antihydrogen as well as on the possibility to perform precision tests on CPT and gravity. At the same time, the trapping of reasonable large numbers of antiprotons has opened up the way for a variety of exciting physics with ultra-low energy antiprotons, ranging from atomic physics issues to nuclear physics and medical applications. I will describe the current status of the work on trapping antiprotons and positrons, discuss possible physics applications of this technique, and describe the two most promising routes to produce antihydrogen for precision spectroscopy. Towards the end a few comments on storing the produced antihydrogen and on utilizing antihydrogen for gravity measurements and for CPT tests are given

Neutral atom traps of radioactives

International Nuclear Information System (INIS)

Behr, J.A.

2003-01-01

Neutral atoms trapped with modern laser cooling techniques offer the promise of improving several broad classes of experiments with radioactive isotopes. In nuclear β decay, neutrino spectroscopy from beta-recoil coincidences, along with highly polarized samples, enable experiments to search for non-Standard Model interactions, test whether parity symmetry is maximally violated, and search for new sources of time reversal violation. Ongoing efforts at TRIUMF, Los Alamos and Berkeley will be highlighted. The traps also offer bright sources for Doppler-free spectroscopy, particularly in high-Z atoms where precision measurements could measure the strength of weak neutral nucleon-nucleon and electron-nucleon interactions. Physics with francium atoms has been vigorously pursued at Stony Brook. Several facilities plan work with radioactive atom traps; concrete plans and efforts at KVI Groningen and Legnaro will be among those summarized. Contributions to the multidisciplinary field of trace analysis will be left up to other presenters

Neutral atom traps of radioactives

CERN Document Server

Behr, J A

2003-01-01

Neutral atoms trapped with modern laser cooling techniques offer the promise of improving several broad classes of experiments with radioactive isotopes. In nuclear beta decay, neutrino spectroscopy from beta-recoil coincidences, along with highly polarized samples, enable experiments to search for non-Standard Model interactions, test whether parity symmetry is maximally violated, and search for new sources of time reversal violation. Ongoing efforts at TRIUMF, Los Alamos and Berkeley will be highlighted. The traps also offer bright sources for Doppler-free spectroscopy, particularly in high-Z atoms where precision measurements could measure the strength of weak neutral nucleon-nucleon and electron-nucleon interactions. Physics with francium atoms has been vigorously pursued at Stony Brook. Several facilities plan work with radioactive atom traps; concrete plans and efforts at KVI Groningen and Legnaro will be among those summarized. Contributions to the multidisciplinary field of trace analysis will be left...

Precise alignment of the collection fiber assisted by real-time plasma imaging in laser-induced breakdown spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Motto-Ros, V., E-mail: vincent.motto-ros@univ-lyon1.fr [Institut Lumière Matière, UMR 5306 Université Lyon 1-CNRS, Université de Lyon, 69622 Villeurbanne cedex (France); Negre, E. [Institut Lumière Matière, UMR 5306 Université Lyon 1-CNRS, Université de Lyon, 69622 Villeurbanne cedex (France); CRITT Matériaux Alsace, 19, rue de St Junien, 67305 Schiltigheim (France); Pelascini, F. [CRITT Matériaux Alsace, 19, rue de St Junien, 67305 Schiltigheim (France); Panczer, G.; Yu, J. [Institut Lumière Matière, UMR 5306 Université Lyon 1-CNRS, Université de Lyon, 69622 Villeurbanne cedex (France)

2014-02-01

Improving the repeatability and the reproducibility of measurement with laser-induced breakdown spectroscopy (LIBS) is one of the actual challenging issues faced by the technique to fit the requirements of precise and accurate quantitative analysis. Among the numerous factors influencing the measurement stability in short and long terms, there are shot-to-shot and day-to-day fluctuations of the morphology of the plasma. Such fluctuations are due to the high sensitivity of laser-induced plasma to experimental conditions including properties of the sample, the laser parameters as well as properties of the ambient gas. In this paper, we demonstrate that precise alignment of the optical fiber for the collection of the plasma emission with respect to the actual morphology of the plasma assisted by real-time imaging, greatly improves the stability of LIBS measurements in short as well as in long terms. The used setup is based on a plasma imaging arrangement using a CCD camera and a real-time image processing. The obtained plasma image is displayed in a 2-dimensional frame where the position of the optical fiber is beforehand calibrated. In addition, the setup provides direct sample surface monitoring, which allows a precise control of the distance between the focusing lens and the sample surface. Test runs with a set of 8 reference samples show very high determination coefficient for calibration curves (R{sup 2} = 0.9999), and a long term repeatability and reproducibility of 4.6% (relative standard deviation) over a period of 3 months without any signal normalization. The capacity of the system to automatically correct the sample surface position for a tilted or non-regular sample surface during a surface mapping measurement is also demonstrated. - Highlights: • Automated alignment of the collection fiber by real-time plasma imaging • High level control of experimental parameters in LIBS experiments • Improvement of the short and long term stability in LIBS

Precise alignment of the collection fiber assisted by real-time plasma imaging in laser-induced breakdown spectroscopy

International Nuclear Information System (INIS)

Motto-Ros, V.; Negre, E.; Pelascini, F.; Panczer, G.; Yu, J.

2014-01-01

Improving the repeatability and the reproducibility of measurement with laser-induced breakdown spectroscopy (LIBS) is one of the actual challenging issues faced by the technique to fit the requirements of precise and accurate quantitative analysis. Among the numerous factors influencing the measurement stability in short and long terms, there are shot-to-shot and day-to-day fluctuations of the morphology of the plasma. Such fluctuations are due to the high sensitivity of laser-induced plasma to experimental conditions including properties of the sample, the laser parameters as well as properties of the ambient gas. In this paper, we demonstrate that precise alignment of the optical fiber for the collection of the plasma emission with respect to the actual morphology of the plasma assisted by real-time imaging, greatly improves the stability of LIBS measurements in short as well as in long terms. The used setup is based on a plasma imaging arrangement using a CCD camera and a real-time image processing. The obtained plasma image is displayed in a 2-dimensional frame where the position of the optical fiber is beforehand calibrated. In addition, the setup provides direct sample surface monitoring, which allows a precise control of the distance between the focusing lens and the sample surface. Test runs with a set of 8 reference samples show very high determination coefficient for calibration curves (R 2 = 0.9999), and a long term repeatability and reproducibility of 4.6% (relative standard deviation) over a period of 3 months without any signal normalization. The capacity of the system to automatically correct the sample surface position for a tilted or non-regular sample surface during a surface mapping measurement is also demonstrated. - Highlights: • Automated alignment of the collection fiber by real-time plasma imaging • High level control of experimental parameters in LIBS experiments • Improvement of the short and long term stability in LIBS measurements

Trapping and Probing Antihydrogen

Energy Technology Data Exchange (ETDEWEB)

Wurtele, Jonathan [UC Berkeley and LBNL

2013-03-27

Precision spectroscopy of antihydrogen is a promising path to sensitive tests of CPT symmetry. The most direct route to achieve this goal is to create and probe antihydrogen in a magnetic minimum trap. Antihydrogen has been synthesized and trapped for 1000s at CERN by the ALPHA Collaboration. Some of the challenges associated with achieving these milestones will be discussed, including mixing cryogenic positron and antiproton plasmas to synthesize antihydrogen with kinetic energy less than the trap potential of .5K. Recent experiments in which hyperfine transitions were resonantly induced with microwaves will be presented. The opportunity for gravitational measurements in traps based on detailed studies of antihydrogen dynamics will be described. The talk will conclude with a discussion future antihydrogen research that will use a new experimental apparatus, ALPHA-I.

Lattice-Assisted Spectroscopy: A Generalized Scanning Tunneling Microscope for Ultracold Atoms.

Science.gov (United States)

Kantian, A; Schollwöck, U; Giamarchi, T

2015-10-16

We propose a scheme to measure the frequency-resolved local particle and hole spectra of any optical lattice-confined system of correlated ultracold atoms that offers single-site addressing and imaging, which is now an experimental reality. Combining perturbation theory and time-dependent density matrix renormalization group simulations, we quantitatively test and validate this approach of lattice-assisted spectroscopy on several one-dimensional example systems, such as the superfluid and Mott insulator, with and without a parabolic trap, and finally on edge states of the bosonic Su-Schrieffer-Heeger model. We highlight extensions of our basic scheme to obtain an even wider variety of interesting and important frequency resolved spectra.

Imaging Optical Frequencies with 100 μ Hz Precision and 1.1 μ m Resolution

Science.gov (United States)

Marti, G. Edward; Hutson, Ross B.; Goban, Akihisa; Campbell, Sara L.; Poli, Nicola; Ye, Jun

2018-03-01

We implement imaging spectroscopy of the optical clock transition of lattice-trapped degenerate fermionic Sr in the Mott-insulating regime, combining micron spatial resolution with submillihertz spectral precision. We use these tools to demonstrate atomic coherence for up to 15 s on the clock transition and reach a record frequency precision of 2.5 ×10-19. We perform the most rapid evaluation of trapping light shifts and record a 150 mHz linewidth, the narrowest Rabi line shape observed on a coherent optical transition. The important emerging capability of combining high-resolution imaging and spectroscopy will improve the clock precision, and provide a path towards measuring many-body interactions and testing fundamental physics.

Precision experiments with antihydrogen: an outlook

International Nuclear Information System (INIS)

Doser, Michael

2011-01-01

After a first generation of experiments has demonstrated the feasibility of forming - in a controlled manner - low-energy antihydrogen atoms via several different techniques, a second generation of experiments is now attempting to trap sufficiently cold atoms, or to form an atomic beam of antihydrogen atoms. The goal of these experiments is to carry out comparative precision spectroscopy between hydrogen and antihydrogen, in view of testing the CPT theorem, either through 1S-2S spectroscopy or via a measurement of the hyperfine splitting of the ground state of antihydrogen. A related class of experiments combines techniques from these experiments with recent developments in the formation of positronium to test the gravitational interaction between matter and antimatter. A significant number of challenges and limitations will still need to be overcome before precision measurements with antihydrogen become feasible, with the next significant milestones being either trapping of antihydrogen or the formation of a beam of antihydrogen.

The LPCTrap facility: A novel transparent Paul trap for high-precision experiments

International Nuclear Information System (INIS)

Rodriguez, D.; Mery, A.; Ban, G.; Bregeault, J.; Darius, G.; Durand, D.; Flechard, X.; Herbane, M.; Labalme, M.; Lienard, E.; Mauger, F.; Merrer, Y.; Naviliat-Cuncic, O.; Thomas, J.C.; Vandamme, C.

2006-01-01

A trap system has been built to perform high-precision β-decay experiments. The system is coupled to the low-energy beam line of the SPIRAL source at GANIL. The continuous ion beam from SPIRAL with energies between 10 and 20keV is slowed down by means of a buffer-gas-filled RFQ trap and ejected thereafter as short ion bunches into a novel transparent Paul trap. Two pulsed cavities located downstream from the RFQ reduce the energy of the ion bunch down to about a hundred eV for an efficient capture in the Paul trap. We describe here the complete system along with the first results obtained with stable He+4, Cl+35 and Ar+36,40 ions from the SPIRAL ECR source. An overall efficiency of 8.7(8)x10 -4 is achieved for 4 He + ions under specific conditions

ATRAP on the way to trapped Antihydrogen

CERN Document Server

Grzonka, D; Gabrielse, G; Goldenbaum, F; Hänsch, T W; Hessels, E A; Larochelle, P; Le Sage, D; Levitt, B; Oelert, W; Pittner, H; Sefzick, T; Speck, A; Storry, C H; Walz, J; Zhang, Z

2005-01-01

The ATRAP experiment at the CERN antiproton decelerator AD aims for a test of the CPT invariance by a high precision comparison of the 1s‐2s transition in the hydrogen and the antihydrogen atom. Antihydrogen production is routinely operated at ATRAP and detailed studies have been performed in order to optimize the production efficiency of useful antihydrogen. The shape parameters of the antiproton and positron clouds, the n‐state distribution of the produced Rydberg antihydrogen atoms and the antihydrogen velocity have been studied. Furthermore an alternative method of laser controlled antihydrogen production was successfully applied. For high precision measurements of atomic transitions cold antihydrogen in the ground state is required which must be trapped due to the low number of available antihydrogen atoms compared to the cold hydrogen beam used for hydrogen spectroscopy. To ensure a reasonable antihydrogen trapping efficiency a magnetic trap has to be superposed the nested Penning trap. First trappi...

Nonlinear spectroscopy of trapped ions

Science.gov (United States)

Schlawin, Frank; Gessner, Manuel; Mukamel, Shaul; Buchleitner, Andreas

2014-08-01

Nonlinear spectroscopy employs a series of laser pulses to interrogate dynamics in large interacting many-body systems, and it has become a highly successful method for experiments in chemical physics. Current quantum optical experiments approach system sizes and levels of complexity that require the development of efficient techniques to assess spectral and dynamical features with scalable experimental overhead. However, established methods from optical spectroscopy of macroscopic ensembles cannot be applied straightforwardly to few-atom systems. Based on the ideas proposed in M. Gessner et al., (arXiv:1312.3365), we develop a diagrammatic approach to construct nonlinear measurement protocols for controlled quantum systems, and we discuss experimental implementations with trapped ion technology in detail. These methods, in combination with distinct features of ultracold-matter systems, allow us to monitor and analyze excitation dynamics in both the electronic and vibrational degrees of freedom. They are independent of system size, and they can therefore reliably probe systems in which, e.g., quantum state tomography becomes prohibitively expensive. We propose signals that can probe steady-state currents, detect the influence of anharmonicities on phonon transport, and identify signatures of chaotic dynamics near a quantum phase transition in an Ising-type spin chain.

Precision Tests of the Electroweak Interaction using Trapped Atoms and Ions

Energy Technology Data Exchange (ETDEWEB)

Melconian, Daniel George [Texas A & M Univ., College Station, TX (United States)

2017-06-21

The objective of the proposed research is to study fundamental aspects of the electroweak interaction via precision measurements in beta decay to test our current understanding of fundamental particles and forces as contained in the so-called "Standard Model" of particle physics. By comparing elegant experiments to rigorous theoretical predictions, we will either confirm the Standard Model to a higher degree and rule out models which seek to extend it, or find evidence of new physics and help guide theorists in developing the New Standard Model. The use of ion and neutral atom traps at radioactive ion beam facilities has opened up a new vista in precision low-energy nuclear physics experiments. Traps provide an ideal source of decaying atoms: they can be extremely cold (~1 mK); they are compact (~1 mm^3); and perhaps most importantly, the daughter particles escape with negligible distortions to their momenta in a scattering-free, open environment. The project is taking advantage of these technologies and applying them to precision beta-decay studies at radioactive beam facilities. The program consists of two complementary efforts: 1) Ion traps are an extremely versatile tool for purifying, cooling and bunching low-energy beams of short-lived nuclei. A large-bore (210~mm) superconducting 7-Tesla solenoid is at the heart of a Penning trap system for which there is a dedicated beamline at T-REX, the upgraded radioactive beam facility at the Cyclotron Institute, Texas A&M University. In addition to providing a general-purpose decay station, the flagship program for this system is measuring the ft-values and beta-neutrino correlation parameters from isospin T=2 superallowed beta-delayed proton decays, complimenting and expanding the already strong program in fundamental interactions at the Institute. 2) A magneto-optical trap is being used at the TRIUMF Neutral Atom Trap facility to observe the (un)polarized angular distribution parameters of isotopes of potassium. We

Dielectrophoresis-Assisted Raman Spectroscopy of Intravesicular Analytes on Metallic Pyramids.

Science.gov (United States)

Barik, Avijit; Cherukulappurath, Sudhir; Wittenberg, Nathan J; Johnson, Timothy W; Oh, Sang-Hyun

2016-02-02

Chemical analysis of membrane-bound containers such as secretory vesicles, organelles, and exosomes can provide insights into subcellular biology. These containers are loaded with a range of important biomolecules, which further underscores the need for sensitive and selective analysis methods. Here we present a metallic pyramid array for intravesicular analysis by combining site-selective dielectrophoresis (DEP) and Raman spectroscopy. Sharp pyramidal tips act as a gradient force generator to trap nanoparticles or vesicles from the solution, and the tips are illuminated by a monochromatic light source for concurrent spectroscopic detection of trapped analytes. The parameters suitable for DEP trapping were optimized by fluorescence microscopy, and the Raman spectroscopy setup was characterized by a nanoparticle based model system. Finally, vesicles loaded with 4-mercaptopyridine were concentrated at the tips and their Raman spectra were detected in real time. These pyramidal tips can perform large-area array-based trapping and spectroscopic analysis, opening up possibilities to detect molecules inside cells or cell-derived vesicles.

Precision Comparison of $\\bar{p}$ and $ p $ Masses in a Penning Trap

CERN Multimedia

2002-01-01

PS196 : Precision Comparison of $\\bar{p}$ and p Masses in a Penning Trap For the first time, antiprotons with energies 10$^{10}$ times lower than those in LEAR can be stored and studied over long times in a small apparatus. The first measurement at this new, low energy frontier is a 1000-fold improvement in the measured antiproton mass. The mass dependent cyclotron frequencies, first for antiprotons then for protons orbiting in the same magnetic field, are compared to establish that the antiproton and proton masses are the same to at least 4~parts in 10$^8$. This is the most stringent test of whether a baryon system is invariant under CPT transformations. A special trap geometry and a superconducting solenoid which cancels fluctuations in the magnetic field in the accelerator hall were crucial to this greatly improved measurement. The current objective is to improve the precision by one or two orders of magnitude. Antiprotons from LEAR at 5.9~MeV, slow below 3~keV via collisions in a thin metal window, and ar...

A New Model of Multiphonon Excitation Trap-Assisted Band-to-Band Tunneling

Directory of Open Access Journals (Sweden)

J. Racko

2012-04-01

Full Text Available The paper describes a new approach to calculating the currents in a pn-diode based on the extension of the Shockley-Read-Hall recombination-generation model. The presented theory is an alternative to Schenk’s model of trap-assisted tunneling. The new approach takes into account generation and recombination as well as tunneling processes in pn-junctions. Using this model, the real “soft” I-V curve usually observed in the case of switching diodes and transistors was modeled as a result of the high concentration of traps that assist in the process of tunneling.

Line-Trapping of Codling Moth (Lepidoptera: Tortricidae): A Novel Approach to Improving the Precision of Capture Numbers in Traps Monitoring Pest Density.

Science.gov (United States)

Adams, C G; McGhee, P S; Schenker, J H; Gut, L J; Miller, J R

2017-08-01

This field study of codling moth, Cydia pomonella (L.), response to single versus multiple monitoring traps baited with codlemone demonstrates that precision of a given capture number is alarmingly poor when the population is held constant by releasing moths. Captures as low as zero and as high as 12 males per single trap are to be expected where the catch mode is three. Here, we demonstrate that the frequency of false negatives and overestimated positives for codling moth trapping can be substantially reduced by employing the tactic of line-trapping, where five traps were deployed 4 m apart along a row of apple trees. Codling moth traps spaced closely competed only slightly. Therefore, deploying five traps closely in a line is a sampling technique nearly as good as deploying five traps spaced widely. But line trapping offers a substantial savings in time and therefore cost when servicing aggregated versus distributed traps. As the science of pest management matures by mastering the ability to translate capture numbers into estimates of absolute pest density, it will be important to employ a tactic like line-trapping so as to shrink the troublesome variability associated with capture numbers in single traps that thwarts accurate decisions about if and when to spray. Line-trapping might similarly increase the reliability and utility of density estimates derived from capture numbers in monitoring traps for various pest and beneficial insects. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America.

4th International Conference on Trapped Charged Particles and Fundamental Physics

CERN Document Server

Comyn, M; Thomson, J; Gwinner, G; TCP'06; TCP 2006

2007-01-01

The TCP06 conference in Parksville on Vancouver Island showcased the impressive progress in the study of fundamental physics using trapped charged particles. Atom and ion trapping has revolutionized atomic physics and related fields. It has proven to be particularly useful for fundamental physics experiments, as the tight control over the particles' degrees of freedom leads to increased precision and efficient use of exotic species such as radioactive atoms or anti-matter. The topics of the meeting included fundamental interactions and symmetries, quantum electrodynamics, quantum state manipulation and quantum information, precision spectroscopy and frequency standards, storage ring physics, highly charged ions in traps, traps for radioactive isotopes, plasmas and collective behaviour, and anti-hydrogen. Highlights from related fields such as fundamental physics studies with neutral, trapped atoms were also presented. The combination of overview articles by leaders in the field and detailed reports on recent ...

X-ray spectroscopy of highly-ionized atoms in an electron beam ion trap (EBIT)

International Nuclear Information System (INIS)

Marrs, R.E.; Bennett, C.; Chen, M.H.

1988-01-01

An Electron Beam Ion Trap at Lawrence Livermore National Laboratory is being used to produce and trap very-highly-charged-ions (q /le/ 70+) for x-ray spectroscopy measurements. Recent measurements of dielectronic recombination, electron impact excitation and transition energies are presented. 15 refs., 12 figs., 1 tab

Excitation transfer and trapping kinetics in plant photosystem I probed by two-dimensional electronic spectroscopy.

Science.gov (United States)

Akhtar, Parveen; Zhang, Cheng; Liu, Zhengtang; Tan, Howe-Siang; Lambrev, Petar H

2018-03-01

Photosystem I is a robust and highly efficient biological solar engine. Its capacity to utilize virtually every absorbed photon's energy in a photochemical reaction generates great interest in the kinetics and mechanisms of excitation energy transfer and charge separation. In this work, we have employed room-temperature coherent two-dimensional electronic spectroscopy and time-resolved fluorescence spectroscopy to follow exciton equilibration and excitation trapping in intact Photosystem I complexes as well as core complexes isolated from Pisum sativum. We performed two-dimensional electronic spectroscopy measurements with low excitation pulse energies to record excited-state kinetics free from singlet-singlet annihilation. Global lifetime analysis resolved energy transfer and trapping lifetimes closely matches the time-correlated single-photon counting data. Exciton energy equilibration in the core antenna occurred on a timescale of 0.5 ps. We further observed spectral equilibration component in the core complex with a 3-4 ps lifetime between the bulk Chl states and a state absorbing at 700 nm. Trapping in the core complex occurred with a 20 ps lifetime, which in the supercomplex split into two lifetimes, 16 ps and 67-75 ps. The experimental data could be modelled with two alternative models resulting in equally good fits-a transfer-to-trap-limited model and a trap-limited model. However, the former model is only possible if the 3-4 ps component is ascribed to equilibration with a "red" core antenna pool absorbing at 700 nm. Conversely, if these low-energy states are identified with the P 700 reaction centre, the transfer-to-trap-model is ruled out in favour of a trap-limited model.

Precise positioning of an ion in an integrated Paul trap-cavity system using radiofrequency signals

Science.gov (United States)

Kassa, Ezra; Takahashi, Hiroki; Christoforou, Costas; Keller, Matthias

2018-03-01

We report a novel miniature Paul ion trap design with an integrated optical fibre cavity which can serve as a building block for a fibre-linked quantum network. In such cavity quantum electrodynamic set-ups, the optimal coupling of the ions to the cavity mode is of vital importance and this is achieved by moving the ion relative to the cavity mode. The trap presented herein features an endcap-style design complemented with extra electrodes on which additional radiofrequency voltages are applied to fully control the pseudopotential minimum in three dimensions. This method lifts the need to use three-dimensional translation stages for moving the fibre cavity with respect to the ion and achieves high integrability, mechanical rigidity and scalability. Not based on modifying the capacitive load of the trap, this method leads to precise control of the pseudopotential minimum allowing the ion to be moved with precisions limited only by the ion's position spread. We demonstrate this by coupling the ion to the fibre cavity and probing the cavity mode profile.

HIGH PRECISION ROVIBRATIONAL SPECTROSCOPY OF OH{sup +}

Energy Technology Data Exchange (ETDEWEB)

Markus, Charles R.; Hodges, James N.; Perry, Adam J.; Kocheril, G. Stephen; McCall, Benjamin J. [Department of Chemistry, University of Illinois, Urbana, IL 61801 (United States); Müller, Holger S. P., E-mail: bjmccall@illinois.edu [I. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, D-50937 Köln (Germany)

2016-02-01

The molecular ion OH{sup +} has long been known to be an important component of the interstellar medium. Its relative abundance can be used to indirectly measure cosmic ray ionization rates of hydrogen, and it is the first intermediate in the interstellar formation of water. To date, only a limited number of pure rotational transitions have been observed in the laboratory making it necessary to indirectly calculate rotational levels from high-precision rovibrational spectroscopy. We have remeasured 30 transitions in the fundamental band with MHz-level precision, in order to enable the prediction of a THz spectrum of OH{sup +}. The ions were produced in a water cooled discharge of O{sub 2}, H{sub 2}, and He, and the rovibrational transitions were measured with the technique Noise Immune Cavity Enhanced Optical Heterodyne Velocity Modulation Spectroscopy. These values have been included in a global fit of field free data to a {sup 3}Σ{sup −} linear molecule effective Hamiltonian to determine improved spectroscopic parameters which were used to predict the pure rotational transition frequencies.

Plans for laser spectroscopy of trapped cold hydrogen-like HCI

International Nuclear Information System (INIS)

Winters, D.F.A.; Abdulla, A.M.; Castrejon Pita, J.R.; Lange, A. de; Segal, D.M.; Thompson, R.C.

2005-01-01

Laser spectroscopy studies are being prepared to measure the 1s ground state hyperfine splitting in trapped cold highly charged ions. The purpose of such experiments is to test quantum electrodynamics in the strong electric field regime. These experiments form part of the HITRAP project at GSI. A brief review of the planned experiments is presented

Trap assisted tunneling and its effect on subthreshold swing of tunnel field effect transistors

OpenAIRE

Sajjad, Redwan N.; Chern, Winston; Hoyt, Judy L.; Antoniadis, Dimitri A.

2016-01-01

We provide a detailed study of the interface Trap Assisted Tunneling (TAT) mechanism in tunnel field effect transistors to show how it contributes a major leakage current path before the Band To Band Tunneling (BTBT) is initiated. With a modified Shockley-Read-Hall formalism, we show that at room temperature, the phonon assisted TAT current always dominates and obscures the steep turn ON of the BTBT current for common densities of traps. Our results are applicable to top gate, double gate and...

High efficiency cyclotron trap assisted positron moderator

OpenAIRE

Gerchow, L.; Cooke, D. A.; Braccini, S.; Döbeli, M.; Kirch, K.; Köster, U.; Müller, A.; Van Der Meulen, N. P.; Vermeulen, C.; Rubbia, A.; Crivelli, P.

2017-01-01

We report the realisation of a cyclotron trap assisted positron tungsten moderator for the conversion of positrons with a broad keV- few MeV energy spectrum to a mono-energetic eV beam with an efficiency of 1.8(2)% defined as the ratio of the slow positrons divided by the $\\beta^+$ activity of the radioactive source. This is an improvement of almost two orders of magnitude compared to the state of the art of tungsten moderators. The simulation validated with this measurement suggests that usi...

Cold molecules: formation, trapping and spectroscopy. - Piling up of cesium dimers in a quadrupolar magnetic trap. - Spectroscopy by lack of photo-association

International Nuclear Information System (INIS)

Vanhaecke, N.

2003-10-01

This thesis deals with the study of cold molecules obtained through the cold atom photo-association technique. Our study is focused both on manipulating external degrees of freedom of these Cs 2 molecules and on studying their internal interactions. A quadrupolar magnetic trap of about 2.10 5 cold Cs 2 molecules is demonstrated. The trap lifetime is on the order of 600 ms, mainly limited by the background gas pressure. The trapped molecules are identified, which allows the determination of the trapped molecule cloud temperature, which is about 35 μK. A dipolar trap is set up by the use of a focused CO 2 laser beam. Moreover, this thesis describes a two-photon photo-association spectroscopy. We report the first study of two-photon photo-association line shapes, which exhibit typical Fano profiles. Taking advantage of the detailed understanding of these line shapes, we measure over one hundred high-lying level energies with an accuracy on the order of 10 MHz. Then we interpret theoretically these energies. The huge hyperfine structure of the Cesium atom binds us to solve a coupled channel Schroedinger equation for internuclear distances above 15 a 0 . Hence we use an asymptotic theory to fit the potential parameters of the Cs 2 dimer. We adjust those parameters by the mean of both evolutionary strategies and deterministic optimum seeking. This is followed by a careful statistics study, which leads to a very accurate determination of the Vander Waals coefficient. Moreover we report the first experimental determination of the exchange interaction amplitude. (author)

A Linear Ion Trap with an Expanded Inscribed Diameter to Improve Optical Access for Fluorescence Spectroscopy

Science.gov (United States)

Rajagopal, Vaishnavi; Stokes, Chris; Ferzoco, Alessandra

2018-02-01

We report a custom-geometry linear ion trap designed for fluorescence spectroscopy of gas-phase ions at ambient to cryogenic temperatures. Laser-induced fluorescence from trapped ions is collected from between the trapping rods, orthogonal to the excitation laser that runs along the axis of the linear ion trap. To increase optical access to the ion cloud, the diameter of the round trapping rods is 80% of the inscribed diameter, rather than the roughly 110% used to approximate purely quadrupolar electric fields. To encompass as much of the ion cloud as possible, the first collection optic has a 25.4 mm diameter and a numerical aperture of 0.6. The choice of geometry and collection optics yields 107 detected photons/s from trapped rhodamine 6G ions. The trap is coupled to a closed-cycle helium refrigerator, which in combination with two 50 Ohm heaters enables temperature control to below 25 K on the rod electrodes. The purpose of the instrument is to broaden the applicability of fluorescence spectroscopy of gas-phase ions to cases where photon emission is a minority relaxation pathway. Such studies are important to understand how the microenvironment of a chromophore influences excited state charge transfer processes.

Trapping-charging ability and electrical properties study of amorphous insulator by dielectric spectroscopy

International Nuclear Information System (INIS)

Mekni, Omar; Arifa, Hakim; Askri, Besma; Yangui, Béchir; Raouadi, Khaled; Damamme, Gilles

2014-01-01

Usually, the trapping phenomenon in insulating materials is studied by injecting charges using a Scanning Electron Microscope. In this work, we use the dielectric spectroscopy technique for showing a correlation between the dielectric properties and the trapping-charging ability of insulating materials. The evolution of the complex permittivity (real and imaginary parts) as a function of frequency and temperature reveals different types of relaxation according to the trapping ability of the material. We found that the space charge relaxation at low frequencies affects the real part of the complex permittivity ε ′ and the dissipation factor Tan(δ). We prove that the evolution of the imaginary part of the complex permittivity against temperature ε ″ =f(T) reflects the phenomenon of charge trapping and detrapping as well as trapped charge evolution Q p (T). We also use the electric modulus formalism to better identify the space charge relaxation. The investigation of trapping or conductive nature of insulating materials was mainly made by studying the activation energy and conductivity. The conduction and trapping parameters are determined using the Correlated Barrier Hopping (CBH) model in order to confirm the relation between electrical properties and charge trapping ability.

Atomistic modeling trap-assisted tunneling in hole tunnel field effect transistors

Science.gov (United States)

Long, Pengyu; Huang, Jun Z.; Povolotskyi, Michael; Sarangapani, Prasad; Valencia-Zapata, Gustavo A.; Kubis, Tillmann; Rodwell, Mark J. W.; Klimeck, Gerhard

2018-05-01

Tunnel Field Effect Transistors (FETs) have the potential to achieve steep Subthreshold Swing (S.S.) below 60 mV/dec, but their S.S. could be limited by trap-assisted tunneling (TAT) due to interface traps. In this paper, the effect of trap energy and location on OFF-current (IOFF) of tunnel FETs is evaluated systematically using an atomistic trap level representation in a full quantum transport simulation. Trap energy levels close to band edges cause the highest leakage. Wave function penetration into the surrounding oxide increases the TAT current. To estimate the effects of multiple traps, we assume that the traps themselves do not interact with each other and as a whole do not modify the electrostatic potential dramatically. Within that model limitation, this numerical metrology study points to the critical importance of TAT in the IOFF in tunnel FETs. The model shows that for Dit higher than 1012/(cm2 eV) IO F F is critically increased with a degraded IO N/IO F F ratio of the tunnel FET. In order to have an IO N/IO F F ratio higher than 104, the acceptable Dit near Ev should be controlled to no larger than 1012/(cm2 eV) .

Precision polarization measurements of atoms in a far-off-resonance optical dipole trap

International Nuclear Information System (INIS)

Fang, F.; Vieira, D. J.; Zhao, X.

2011-01-01

Precision measurement of atomic and nuclear polarization is an essential step for beta-asymmetry measurement of radioactive atoms. In this paper, we report the polarization measurement of Rb atoms in an yttrium-aluminum-garnet (YAG) far-off-resonance optical dipole trap. We have prepared a cold cloud of polarized Rb atoms in the YAG dipole trap by optical pumping and achieved an initial nuclear polarization of up to 97.2(5)%. The initial atom distribution in different Zeeman levels is measured by using a combination of microwave excitation, laser pushing, and atomic retrap techniques. The nuclear-spin polarization is further purified to 99.2(2)% in 10 s and maintained above 99% because the two-body collision loss rate between atoms in mixed spin states is greater than the one-body trap loss rate. Systematic effects on the nuclear polarization, including the off-resonance Raman scattering, magnetic field gradient, and background gas collisions, are discussed.

In Situ Raman Spectroscopy of COOH-Functionalized SWCNTs Trapped with Optoelectronic Tweezers

Directory of Open Access Journals (Sweden)

Peter J. Pauzauskie

2012-01-01

Full Text Available Optoelectronic tweezers (OETs were used to trap and deposit aqueous dispersions of carboxylic-acid-functionalized single-walled carbon nanotube bundles. Dark-field video microscopy was used to visualize the dynamics of the bundles both with and without virtual electrodes, showing rapid accumulation of carbon nanotubes when optical virtual electrodes are actuated. Raman microscopy was used to probe SWCNT materials following deposition onto metallic fiducial markers as well as during trapping. The local carbon nanotube concentration was observed to increase rapidly during trapping by more than an order of magnitude in less than one second due to localized optical dielectrophoresis forces. This combination of enrichment and spectroscopy with a single laser spot suggests a broad range of applications in physical, chemical, and biological sciences.

Spectroscopy of Deep Traps in Cu2S-CdS Junction Structures

Directory of Open Access Journals (Sweden)

Eugenijus Gaubas

2012-12-01

Full Text Available Cu2S-CdS junctions of the polycrystalline material layers have been examined by combining the capacitance deep level transient spectroscopy technique together with white LED light additional illumination (C-DLTS-WL and the photo-ionization spectroscopy (PIS implemented by the photocurrent probing. Three types of junction structures, separated by using the barrier capacitance characteristics of the junctions and correlated with XRD distinguished precipitates of the polycrystalline layers, exhibit different deep trap spectra within CdS substrates.

Mathematical modeling of elementary trapping-reduction processes in positron annihilation lifetime spectroscopy: methodology of Ps-to-positron trapping conversion

Science.gov (United States)

Shpotyuk, Ya; Cebulski, J.; Ingram, A.; Shpotyuk, O.

2017-12-01

Methodological possibilities of positron annihilation lifetime (PAL) spectroscopy in application to nanostructurized substances treated within three-term fitting procedure are reconsidered to parameterize their atomic-deficient structural arrangement. In contrast to conventional three-term fitting analysis of the detected PAL spectra based on admixed positron trapping and positronium (Ps) decaying, the nanostructurization due to guest nanoparticles embedded in host matrix is considered as producing modified trapping, which involves conversion between these channels. The developed approach referred to as x3-x2-coupling decomposition algorithm allows estimation free volumes of interfacial voids responsible for positron trapping and bulk lifetimes in nanoparticle-embedded substances. This methodology is validated using experimental data of Chakraverty et al. [Phys. Rev. B71 (2005) 024115] on PAL study of composites formed by guest NiFe2O4 nanocrystals grown in host SiO2 matrix.

Spectroscopy of Charge Carriers and Traps in Field-Doped Single Crystal Organic Semiconductors

Energy Technology Data Exchange (ETDEWEB)

Zhu, Xiaoyang [Columbia Univ., New York, NY (United States); Frisbie, Daniel [Univ. of Minnesota, Minneapolis, MN (United States)

2017-03-31

The proposed research aims to achieve quantitative, molecular level understanding of charge carriers and traps in field-doped crystalline organic semiconductors via in situ linear and nonlinear optical spectroscopy, in conjunction with transport measurements and molecular/crystal engineering.

Optical trapping and Raman spectroscopy of single nanostructures using standing-wave Raman tweezers

Science.gov (United States)

Wu, Mu-ying; He, Lin; Chen, Gui-hua; Yang, Guang; Li, Yong-qing

2017-08-01

Optical tweezers integrated with Raman spectroscopy allows analyzing a single trapped micro-particle, but is generally less effective for individual nano-sized objects in the 10-100 nm range. The main challenge is the weak gradient force on nanoparticles that is insufficient to overcome the destabilizing effect of scattering force and Brownian motion. Here, we present standing-wave Raman tweezers for stable trapping and sensitive characterization of single isolated nanostructures with a low laser power by combining a standing-wave optical trap (SWOT) with confocal Raman spectroscopy. This scheme has stronger intensity gradients and balanced scattering forces, and thus is more stable and sensitive in measuring nanoparticles in liquid with 4-8 fold increase in the Raman signals. It can be used to analyze many nanoparticles that cannot be measured with single-beam Raman tweezers, including individual single-walled carbon nanotubes (SWCNT), graphene flakes, biological particles, polystyrene beads (100 nm), SERS-active metal nanoparticles, and high-refractive semiconductor nanoparticles with a low laser power of a few milliwatts. This would enable sorting and characterization of specific SWCNTs and other nanoparticles based on their increased Raman fingerprints.

6th International Conference on Trapped Charged Particles and Fundamental Physics

CERN Document Server

Schury, Peter; Ichikawa, Yuichi

2017-01-01

This volume presents the proceedings of the International Conference on Trapped Charged Particles and Fundamental Physics (TCP 14). It presents recent developments in the theoretical and experimental research on trapped charged particles and related fundamental physics and applications. The content has been divided topic-wise covering basic questions of Fundamental Physics, Quantum and QED Effects, Plasmas and Collective Behavior and Anti-Hydrogen. More technical issues include Storage Ring Physics, Precision Spectroscopy and Frequency Standards, Highly Charged Ions in Traps, Traps for Radioactive Isotopes and New Techniques and Facilities. An applied aspect of ion trapping is discussed in section devoted to Applications of Particle Trapping including Quantum Information and Processing. Each topic has a more general introduction, but also more detailed contributions are included. A selection of contributions exemplifies the interdisciplinary nature of the research on trapped charged particles worldwide. Repri...

Determination of the trap-assisted recombination strength in polymer light emitting diodes

NARCIS (Netherlands)

Kuik, Martijn; Nicolai, Herman T.; Lenes, Martijn; Wetzelaer, Gert-Jan A. H.; Lu, Mingtao; Blom, Paul W. M.

2011-01-01

The recombination processes in poly(p-phenylene vinylene) based polymer light-emitting diodes (PLEDs) are investigated. Photogenerated current measurements on PLED device structures reveal that next to the known Langevin recombination also trap-assisted recombination is an important recombination

Determination of the trap-assisted recombination strength in polymer light emitting diodes

NARCIS (Netherlands)

Kuik, M.; Nicolai, H.T.; Lenes, M.; Wetzelaer, G.-J.A.H.; Lu, M.; Blom, P.W.M.

2011-01-01

The recombination processes in poly(p -phenylene vinylene) based polymer light-emitting diodes (PLEDs) are investigated. Photogenerated current measurements on PLED device structures reveal that next to the known Langevin recombination also trap-assisted recombination is an important recombination

Precision mass measurements at THe-trap and the FSU trap

Energy Technology Data Exchange (ETDEWEB)

Hoecker, Martin Juergen

2016-07-26

THe-Trap is a Penning-trap mass spectrometer at the Max-Planck-Institute for Nuclear Physics in Heidelberg, Germany, that aims to measure the T/{sup 3}He mass ratio with a relative uncertainty of 10{sup -11}. Improvements of the measurement technique, in particular the measurement of systematic shifts, enabled measurements of mass ratios with relative uncertainties of 7.10{sup -11}, as demonstrated by a cyclotron frequency ratio determination on {sup 12}C{sup 4+}/{sup 16}O{sup 5+}. This uncertainty was limited by the lineshape. An improved theoretical model based on a rotating wave approximation can be used to describe dynamical interactions between the detection system and the ion, in order to better understand the lineshape and to further reduce the uncertainty. The Florida State University trap is a Penning-trap mass spectrometer located in Tallahassee, Florida (USA). In the context of this thesis, three mass ratios were measured, and further 20 mass ratio measurements analyzed, which resulted in the publication of the masses of {sup 82,83}Kr, {sup 131,134}Xe, {sup 86-88}Sr, and {sup 170-174,176}Yb with relative uncertainties between (0.9 - 1.3).10{sup -10}. These masses serve as reference masses for other experiments and have applications in the determination of the fine-structure constant alpha via the photon-recoil method.

Capacity spectroscopy of minority-carrier radiation traps in n-type silicon

International Nuclear Information System (INIS)

Kuchinskij, P.V.; Lomako, V.M.; Shakhlevich, L.N.

1987-01-01

Minority charge-carrier radiation traps in n-silicon, produced by neutron transmutation doping (NTD) and zone melting method, were studied using unsteady capacity spectroscopy method. Studying the parameters of defects, formed in the lower half of the restricted zone, was performed using minority carrier injection by forward current pulses. Samples were p + -n-structures, produced on the basis of silicon with different oxygen content. It is shown, that a trap with activation energy ≅E v +0.34 eV appears to be the main defect in oxygen p-silicon. Investigation into thermal stability has shown, that centers with E v +0.34 eV and E v +0.27 eV activation energies are annealed within the same temperature interval (300-400 deg C)

Synthesis of antihydrogen atoms in a CUSP trap

Energy Technology Data Exchange (ETDEWEB)

Kuroda, Naofumi, E-mail: kuroda@phys.c.u-tokyo.ac.jp [University of Tokyo, Graduate School of Arts and Sciences (Japan); Enomoto, Yoshinori [RIKEN Advanced Science Institute (Japan); Michishio, Koji [Tokyo University of Science, Department of Physics (Japan); Kim, Chanhyoun [University of Tokyo, Graduate School of Arts and Sciences (Japan); Higaki, Hiroyuki [Hiroshima University, Graduate School of Advanced Science of Matter (Japan); Nagata, Yugo; Kanai, Yasuyuki [RIKEN Advanced Science Institute (Japan); Torii, Hiroyuki A. [University of Tokyo, Graduate School of Arts and Sciences (Japan); Corradini, Maurizzio; Leali, Marco; Lodi-Rizzini, Evandro; Mascagna, Valerio; Venturelli, Luca; Zurlo, Nicola [Universita di Brescia and Instituto Nazionale di Fisica Nucleare, Dipartimento di Chimica e Fisica per l' Ingegneria e per i Materiali (Italy); Fujii, Koki; Ohtsuka, Miki; Tanaka, Kazuo [University of Tokyo, Graduate School of Arts and Sciences (Japan); Imao, Hiroshi [RIKEN Nishina Center for Accelerator-Based Science (Japan); Nagashima, Yasuyuki [Tokyo University of Science, Department of Physics (Japan); Matsuda, Yasuyuki [University of Tokyo, Graduate School of Arts and Sciences (Japan); and others

2012-05-15

ASACUSA collaboration has been making a path to realize high precision microwave spectroscopy of ground-state hyperfine transitions of antihydrogen atom in flight for stringent test of the CPT symmetry. Recently, we have succeeded in synthesizing our first cold antihydrogen atoms employing a CUSP trap. It is expected that synthesized antihydrogen atoms in the low-field-seeking states are preferentially focused along the cusp magnetic field axis whereas those in the high-field-seeking states are not focused, resulting in the formation of a spin-polarized antihydrogen beam. We report the recent results of antihydrogen atom synthesis and beam production developed with the CUSP trap.

Synthesis of antihydrogen atoms in a CUSP trap

International Nuclear Information System (INIS)

Kuroda, Naofumi; Enomoto, Yoshinori; Michishio, Koji; Kim, Chanhyoun; Higaki, Hiroyuki; Nagata, Yugo; Kanai, Yasuyuki; Torii, Hiroyuki A.; Corradini, Maurizzio; Leali, Marco; Lodi-Rizzini, Evandro; Mascagna, Valerio; Venturelli, Luca; Zurlo, Nicola; Fujii, Koki; Ohtsuka, Miki; Tanaka, Kazuo; Imao, Hiroshi; Nagashima, Yasuyuki; Matsuda, Yasuyuki

2012-01-01

ASACUSA collaboration has been making a path to realize high precision microwave spectroscopy of ground-state hyperfine transitions of antihydrogen atom in flight for stringent test of the CPT symmetry. Recently, we have succeeded in synthesizing our first cold antihydrogen atoms employing a CUSP trap. It is expected that synthesized antihydrogen atoms in the low-field-seeking states are preferentially focused along the cusp magnetic field axis whereas those in the high-field-seeking states are not focused, resulting in the formation of a spin-polarized antihydrogen beam. We report the recent results of antihydrogen atom synthesis and beam production developed with the CUSP trap.

Photo-excited charge collection spectroscopy probing the traps in field-effect transistors

CERN Document Server

Im, Seongil; Kim, Jae Hoon

2013-01-01

Solid state field-effect devices such as organic and inorganic-channel thin-film transistors (TFTs) have been expected to promote advances in display and sensor electronics. The operational stabilities of such TFTs are thus important, strongly depending on the nature and density of charge traps present at the channel/dielectric interface or in the thin-film channel itself. This book contains how to characterize these traps, starting from the device physics of field-effect transistor (FET). Unlike conventional analysis techniques which are away from well-resolving spectral results, newly-introduced photo-excited charge-collection spectroscopy (PECCS) utilizes the photo-induced threshold voltage response from any type of working transistor devices with organic-, inorganic-, and even nano-channels, directly probing on the traps. So, our technique PECCS has been discussed through more than ten refereed-journal papers in the fields of device electronics, applied physics, applied chemistry, nano-devices and materia...

A novel low cost pulse excitation source to study trap spectroscopy of persistent luminescent materials

Science.gov (United States)

Chandrasekhar, Ngangbam; Singh, Nungleppam Monorajan; Gartia, R. K.

2018-04-01

Luminescent techniques require one or the other source of excitations which may vary from high cost X-rays, γ-rays, β-rays etc. to low cost LED. Persistent luminescent materials or Glow-in-the-Dark phosphors are the optical harvesters which store the optical energy from day light illuminating a whole night. They are so sensitive that they can be excited even with the low light of firefly. Therefore, instead of using a high cost excitation source authors have developed a low cost functioning of excitation source controlling short pulses of LED to excite persistent phosphors with the aid of ExpEYES Junior (Hardware/software framework developed by IUAC, New Delhi). Using this, the authors have excited the sample under investigation upto 10 ms. Trap spectroscopy of the pre-excited sample with LED is studied using Thermoluminescence (TL) technique. In this communication, development of the excitation source is discussed and demonstrate the its usefulness in the study of trap spectroscopy of commercially available CaS:Eu2+, Sm3+. Trapping parameters are also evaluated using Computerized Glow Curve Deconvolution (CGCD) technique.

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).

Double-trap measurement of the proton magnetic moment at 0.3 parts per billion precision.

Science.gov (United States)

Schneider, Georg; Mooser, Andreas; Bohman, Matthew; Schön, Natalie; Harrington, James; Higuchi, Takashi; Nagahama, Hiroki; Sellner, Stefan; Smorra, Christian; Blaum, Klaus; Matsuda, Yasuyuki; Quint, Wolfgang; Walz, Jochen; Ulmer, Stefan

2017-11-24

Precise knowledge of the fundamental properties of the proton is essential for our understanding of atomic structure as well as for precise tests of fundamental symmetries. We report on a direct high-precision measurement of the magnetic moment μ p of the proton in units of the nuclear magneton μ N The result, μ p = 2.79284734462 (±0.00000000082) μ N , has a fractional precision of 0.3 parts per billion, improves the previous best measurement by a factor of 11, and is consistent with the currently accepted value. This was achieved with the use of an optimized double-Penning trap technique. Provided a similar measurement of the antiproton magnetic moment can be performed, this result will enable a test of the fundamental symmetry between matter and antimatter in the baryonic sector at the 10 -10 level. Copyright © 2017, American Association for the Advancement of Science.

High-Precision Mass Measurements of Exotic Nuclei with the Triple-Trap Mass Spectrometer Isoltrap

CERN Multimedia

Blaum, K; Zuber, K T; Stanja, J

2002-01-01

The masses of close to 200 short-lived nuclides have already been measured with the mass spectrometer ISOLTRAP with a relative precision between 1$\\times$10$^{-7}$ and 1$\\times$10^{-8}$. The installatin of a radio-frequency quadrupole trap increased the overall efficiency by two orders of magnitude which is at present about 1%. In a recent upgrade, we installed a carbon cluster laser ion source, which will allow us to use carbon clusters as mass references for absolute mass measurements. Due to these improvements and the high reliability of ISOLTRAP we are now able to perform accurate high-precision mass measurements all over the nuclear chart. We propose therefore mass measurements on light, medium and heavy nuclides on both sides of the valley of stability in the coming four years. ISOLTRAP is presently the only instrument capable of the high precision required for many of the proposed studies.

Combining optical trapping in a microfluidic channel with simultaneous micro-Raman spectroscopy and motion detection

Science.gov (United States)

Lawton, Penelope F.; Saunter, Christopher D.; Girkin, John M.

2014-03-01

Since their invention by Ashkin optical tweezers have demonstrated their ability and versatility as a non-invasive tool for micromanipulation. One of the most useful additions to the basic optical tweezers system is micro-Raman spectroscopy, which permits highly sensitive analysis of single cells or particles. We report on the development of a dual laser system combining two spatial light modulators to holographically manipulate multiple traps (at 1064nm) whilst undertaking Raman spectroscopy using a 532nm laser. We can thus simultaneously trap multiple particles and record their Raman spectra, without perturbing the trapping system. The dual beam system is built around micro-fluidic channels where crystallisation of calcium carbonate occurs on polymethylmethacrylate (PMMA) beads. The setup is designed to simulate at a microscopic level the reactions that occur on items in a dishwasher, where permanent filming of calcium carbonate on drinking glasses is a problem. Our system allows us to monitor crystal growth on trapped particles in which the Raman spectrum and changes in movement of the bead are recorded. Due to the expected low level of crystallisation on the bead surfaces this allows us to obtain results quickly and with high sensitivity. The long term goal is to study the development of filming on samples in-situ with the microfl.uidic system acting as a model dishwasher.

Trapping radioactive ions

CERN Document Server

Kluge, Heinz-Jürgen

2004-01-01

Trapping devices for atomic and nuclear physics experiments with radioactive ions are becoming more and more important at accelerator facilities. While about ten years ago only one online Penning trap experiment existed, namely ISOLTRAP at ISOLDE/CERN, meanwhile almost every radioactive beam facility has installed or plans an ion trap setup. This article gives an overview on ion traps in the operation, construction or planing phase which will be used for fundamental studies with short-lived radioactive nuclides such as mass spectrometry, laser spectroscopy and nuclear decay spectroscopy. In addition, this article summarizes the use of gas cells and radiofrequency quadrupole (Paul) traps at different facilities as a versatile tool for ion beam manipulation like retardation, cooling, bunching, and cleaning.

Trapping radioactive ions

International Nuclear Information System (INIS)

Kluge, H.-J.; Blaum, K.

2004-01-01

Trapping devices for atomic and nuclear physics experiments with radioactive ions are becoming more and more important at accelerator facilities. While about ten years ago only one online Penning trap experiment existed, namely ISOLTRAP at ISOLDE/CERN, meanwhile almost every radioactive beam facility has installed or plans an ion trap setup. This article gives an overview on ion traps in the operation, construction or planing phase which will be used for fundamental studies with short-lived radioactive nuclides such as mass spectrometry, laser spectroscopy and nuclear decay spectroscopy. In addition, this article summarizes the use of gas cells and radiofrequency quadrupole (Paul) traps at different facilities as a versatile tool for ion beam manipulation like retardation, cooling, bunching, and cleaning

Optical trapping and Feshbach spectroscopy of an ultracold Rb-Cs mixture

International Nuclear Information System (INIS)

Pilch, K.

2009-01-01

We investigate quantum-mechanical interactions between ultracold rubidium and cesium in an optical trap at temperatures of a few micro kelvin. Our results provide, on the one hand, an experimental key to understand the collisional properties and, on the other hand, a tool to control the interspecies interactions. By performing loss measurements we locate several Feshbach resonances, which provide insight into the energy structure of weakly bound RbCs molecules near the dissociation threshold and allow for the production of such heteronuclear Feshbach molecules. In the future we will transfer these loosely-bound molecules into the absolute internal ground state. The availability of ultracold heteronuclear ground state molecules will open the door to investigate phenomena associated with ultracold polar quantum gases. In our new experimental set-up we are able to trap and cool rubidium and cesium atoms in their lowest internal states. First we load both species into a two-color magneto-optical trap, having full control over the single-species atom number. We extend the technique of degenerate Raman-sideband cooling to a two-color version, which is able to simultaneously cool and polarize both rubidium and cesium. Thereafter we load the atoms into a levitated crossed optical dipole trap. Because of the presence of the gradient magnetic field the trap is highly state selective and consequently provides perfect spin-polarization of the sample. Furthermore, a coincidence of the magnetic-moment-to-mass ratios of the two species allows for simultaneous levitation of both, which assures an almost perfect spatial overlap between the species. We perform Feshbach spectroscopy in two dierent spin channels of the mixture within a magnetic field ranging from 20 to 300 Gauss. In the lowest spin combination of the species we locate 23 interspecies Feshbach resonances, while in a higher spin mixture we find 2 resonances. The high number of resonances found within this range of

Unraveling surface and bulk trap states in lead halide perovskite solar cells using impedance spectroscopy

Science.gov (United States)

Han, Changfeng; Wang, Kai; Zhu, Xixiang; Yu, Haomiao; Sun, Xiaojuan; Yang, Qin; Hu, Bin

2018-03-01

Organic-inorganic hybrid perovskites (OIHPs) have been widely recognized as an excellent candidate for next-generation photovoltaic materials because of their highly efficient power conversion. Acquiring a complete understanding of trap states and dielectric properties in OIHP-based solar cells at the steady state is highly desirable in order to further explore and improve their optoelectronic functionalities and properties. We report CH3NH3PbI3-x Cl x -based planar solar cells with a power conversion efficiency (PCE) of 15.8%. The illumination intensity dependence of the current density-voltage (J-V) revealed the presence of trap-assisted recombination at low fluences. Non-destructive ac impedance spectroscopy (ac-IS) was applied to characterize the device at the steady state. The capacitance-voltage (C-V) spectra exhibited some distinct variations at a wide range of ac modulation frequencies with and without photo-excitations. Since the frequency-dependent chemical capacitance ({{C}μ }) is concerned with the surface and bulk related density of states (DOS) in CH3NH3PbI3-x Cl x , we verified this by fitting the corresponding DOS by a Gaussian distribution function. We ascertained that the electronic sub-gap trap states present in the solution processed CH3NH3PbI3-x Cl x and their distribution differs from the surface to the bulk. In fact, we demonstrated that both surfaces that were adjacent to the electron and hole transport layers featured analogous DOS. Despite this, photo- and bias-induced giant dielectric responses (i.e. both real and imaginary parts) were detected. A remarkable reduction of {{C}μ } at higher frequencies (i.e. more than 100 kHz) was ascribed to the effect of dielectric loss in CH3NH3PbI3-x Cl x .

The Ramsey method in high-precision mass spectrometry with Penning traps Experimental results

CERN Document Server

George, S; Herfurth, F; Herlert, A; Kretzschmar, M; Nagy, S; Schwarz, S; Schweikhard, L; Yazidjian, C

2007-01-01

The highest precision in direct mass measurements is obtained with Penning trap mass spectrometry. Most experiments use the interconversion of the magnetron and cyclotron motional modes of the stored ion due to excitation by external radiofrequency-quadrupole fields. In this work a new excitation scheme, Ramsey's method of time-separated oscillatory fields, has been successfully tested. It has been shown to reduce significantly the uncertainty in the determination of the cyclotron frequency and thus of the ion mass of interest. The theoretical description of the ion motion excited with Ramsey's method in a Penning trap and subsequently the calculation of the resonance line shapes for different excitation times, pulse structures, and detunings of the quadrupole field has been carried out in a quantum mechanical framework and is discussed in detail in the preceding article in this journal by M. Kretzschmar. Here, the new excitation technique has been applied with the ISOLTRAP mass spectrometer at ISOLDE/CERN fo...

Raman spectroscopy of individual monocytes reveals that single-beam optical trapping of mononuclear cells occurs by their nucleus

International Nuclear Information System (INIS)

Fore, Samantha; Chan, James; Taylor, Douglas; Huser, Thomas

2011-01-01

We show that laser tweezers Raman spectroscopy of eukaryotic cells with a significantly larger diameter than the tight focus of a single-beam laser trap leads to optical trapping of the cell by its optically densest part, i.e. typically the cell's nucleus. Raman spectra of individual optically trapped monocytes are compared with location-specific Raman spectra of monocytes adhered to a substrate. When the cell's nucleus is stained with a fluorescent live cell stain, the Raman spectrum of the DNA-specific stain is observed only in the nucleus of individual monocytes. Optically trapped monocytes display the same behavior. We also show that the Raman spectra of individual monocytes exhibit the characteristic Raman signature of cells that have not yet fully differentiated and that individual primary monocytes can be distinguished from transformed monocytes based on their Raman spectra. This work provides further evidence that laser tweezers Raman spectroscopy of individual cells provides meaningful biochemical information in an entirely non-destructive fashion that permits discerning differences between cell types and cellular activity

Design of a high field uniformity electromagnet for Penning trap

International Nuclear Information System (INIS)

Itteera, Janvin; Singh, Kumud; Teotia, Vikas; Ukarde, Priti; Malhotra, Sanjay; Taly, Y.K.; Joshi, Manoj; Rao, Pushpa

2013-01-01

An ion trap (Penning trap) facility is being developed at BARC for spectroscopy studies. This requires the design of an iron core electromagnet capable of generating high magnetic fields (∼1.7T) at the centre of an 88 mm long air gap. This electromagnet provides the requisite dipole magnetic field which when superimposed on the electrostatic quadrupoles ensures a stable trapping of ions. To conduct high precision spectroscopy studies, we need to ensure a high degree of magnetic field uniformity ( 3 volume (Trap zone). Various pole shoe profiles were studied and modelled, FEM simulation of the same were conducted to compute the magnetic field intensity and field uniformity. Owing to the large air gap and requirement of high field intensity in the GFR, the exciting coils need to handle high current densities, which require water cooled systems. Double Pan-Cake coil design is selected for powering the magnet. Electrical, thermal and hydraulic designs of the coils are completed and a prototype double pancake coil was fabricated and tested for verifying the electrical and thermal parameter. The spatial field homogeneity is achieved by shimming the pole tip. Temporal stability of magnet requires a highly stable power supply for exciting the coils and its stability class is derived from FEM simulations. This paper discusses the electromagnetic design and development of the penning trap magnet being developed at BARC. (author)

Storage ion trap of an 'In-Flight Capture' type for precise mass measurement of radioactive nuclear reaction products and fission fragments

International Nuclear Information System (INIS)

Tarantin, N.I.

2001-01-01

Data on nuclear masses provide a basis for creating and testing various nuclear models. A tandem system of FLNR comprised of the U-400M cyclotron, the COMBAS magnetic separator and the mass-spectrometric ion trap of an 'in-flight capture' type is considered as a possible complex for producing of the short-lived nuclei in fragmentation reactions by heavy ions and for precise mass measurement of these nuclei. The plan of scientific and technical FLNR research includes a project DRIBs for producing beams of accelerated radioactive nuclear reaction products and photofission fragments. This project proposes also precise mass measurements of the fission fragment with the help of the ion trap. The in-flight entrance of the ions and their capture in the mass-spectrometric ion trap using the monochromatizing degrader, the static electric and magnetic fields and a new invention, a magnetic unidirectional transporting ventil, is considered

Fundamental physics in particle traps

International Nuclear Information System (INIS)

Quint, Wolfgang; Vogel, Manuel

2014-01-01

The individual topics are covered by leading experts in the respective fields of research. Provides readers with present theory and experiments in this field. A useful reference for researchers. This volume provides detailed insight into the field of precision spectroscopy and fundamental physics with particles confined in traps. It comprises experiments with electrons and positrons, protons and antiprotons, antimatter and highly charged ions, together with corresponding theoretical background. Such investigations represent stringent tests of quantum electrodynamics and the Standard model, antiparticle and antimatter research, test of fundamental symmetries, constants, and their possible variations with time and space. They are key to various aspects within metrology such as mass measurements and time standards, as well as promising to further developments in quantum information processing. The reader obtains a valuable source of information suited for beginners and experts with an interest in fundamental studies using particle traps.

Penning Trap Experiments with the Most Exotic Nuclei on Earth: Precision Mass Measurements of Halo Nuclei

Science.gov (United States)

Brodeur, M.; Brunner, T.; Ettenauer, S.; Lapierre, A.; Ringle, R.; Delheij, P.; Dilling, J.

2009-05-01

Exotic nuclei are characterized with an extremely unbalanced protons-neutrons ratio (p/n) where for instance, the halo isotopes of He and Li have up to 3X more n than p (compared to p/n = 1 in ^12C). The properties of these exotic halo nuclei have long been recognized as the most stringent tests of our understanding of the strong force. ^11Li belongs to a special category of halos called Borromean, bound as a three-body family, while the two-body siblings, ^10Li and 2 n, are unbound as separate entities. Last year, a first mass measurement of the radioisotope ^11Li using a Penning trap spectrometer was carried out at the TITAN (Triumf's Ion Trap for Atomic and Nuclear science) facility at TRIUMF-ISAC. Penning traps are proven to be the most precise device to make mass measurements, yet until now they were unable to reach these nuclei. At TRIUMF we managed to measure the mass of ^11Li to an unprecedented precision of dm/m = 60 ppb, which is remarkable since it has a half-life of only 8.8 ms which it the shortest-lived nuclide to be measured with this technique. Furthermore, new and improved masses for the 2 and 4 n halo ^6,8He, as well has the 1 n halo ^11Be have been performed. An overview of the TITAN mass measurement program and its impact in understanding the most exotic nuclei will be given.

Detection of free radicals by radical trapping and 15N NMR spectroscopy in copolymerization of methyl acrylate and styrene

NARCIS (Netherlands)

Kelemen, P.; Klumperman, B.

2003-01-01

The macroradicals taking part in the copolymn. of Me acrylate and styrene were trapped by reaction with a 15N labeled stable nitroxyl radical at 70 DegC. The nitroxyl radical is formed in situ from a thermally instable alkoxyamine precursor. 15N NMR spectroscopy is applied to detect the trapping

A trap-based pulsed positron beam optimised for positronium laser spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Cooper, B. S., E-mail: ben.cooper.13@ucl.ac.uk; Alonso, A. M.; Deller, A.; Wall, T. E.; Cassidy, D. B. [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom)

2015-10-15

We describe a pulsed positron beam that is optimised for positronium (Ps) laser-spectroscopy experiments. The system is based on a two-stage Surko-type buffer gas trap that produces 4 ns wide pulses containing up to 5 × 10{sup 5} positrons at a rate of 0.5-10 Hz. By implanting positrons from the trap into a suitable target material, a dilute positronium gas with an initial density of the order of 10{sup 7} cm{sup −3} is created in vacuum. This is then probed with pulsed (ns) laser systems, where various Ps-laser interactions have been observed via changes in Ps annihilation rates using a fast gamma ray detector. We demonstrate the capabilities of the apparatus and detection methodology via the observation of Rydberg positronium atoms with principal quantum numbers ranging from 11 to 22 and the Stark broadening of the n = 2 → 11 transition in electric fields.

Atomization efficiency and photon yield in laser-induced breakdown spectroscopy analysis of single nanoparticles in an optical trap

Science.gov (United States)

Purohit, Pablo; Fortes, Francisco J.; Laserna, J. Javier

2017-04-01

Laser-induced breakdown spectroscopy (LIBS) was employed for investigating the influence of particle size on the dissociation efficiency and the absolute production of photons per mass unit of airborne solid graphite spheres under single-particle regime. Particles of average diameter of 400 nm were probed and compared with 2 μm particles. Samples were first catapulted into aerosol form and then secluded in an optical trap set by a 532 nm laser. Trap stability was quantified before subjecting particles to LIBS analysis. Fine alignment of the different lines comprising the optical catapulting-optical trapping-laser-induced breakdown spectroscopy instrument and tuning of excitation parameters conditioning the LIBS signal such as fluence and acquisition delay are described in detail with the ultimate goal of acquiring clear spectroscopic data on masses as low as 75 fg. The atomization efficiency and the photon yield increase as the particle size becomes smaller. Time-resolved plasma imaging studies were conducted to elucidate the mechanisms leading to particle disintegration and excitation.

A source of antihydrogen for in-flight hyperfine spectroscopy

CERN Document Server

Kuroda, N; Murtagh, D J; Van Gorp, S; Nagata, Y; Diermaier, M; Federmann, S; Leali, M; Malbrunot, C; Mascagna, V; Massiczek, O; Michishio, K; Mizutani, T; Mohri, A; Nagahama, H; Ohtsuka, M; Radics, B; Sakurai, S; Sauerzopf, C; Suzuki, K; Tajima, M; Torii, H A; Venturelli, L; Wünschek, B; Zmeskal, J; Zurlo, N; Higaki, H; Kanai, Y; Lodi Rizzini, E; Nagashima, Y; Matsuda, Y; Widmann, E; Yamazaki, Y

2014-01-01

Antihydrogen, a positron bound to an antiproton, is the simplest antiatom. Its counterpart—hydrogen—is one of the most precisely investigated and best understood systems in physics research. High-resolution comparisons of both systems provide sensitive tests of CPT symmetry, which is the most fundamental symmetry in the Standard Model of elementary particle physics. Any measured difference would point to CPT violation and thus to new physics. Here we report the development of an antihydrogen source using a cusp trap for in-flight spectroscopy. A total of 80 antihydrogen atoms are unambiguously detected 2.7 m downstream of the production region, where perturbing residual magnetic fields are small. This is a major step towards precision spectroscopy of the ground-state hyperfine splitting of antihydrogen using Rabi-like beam spectroscopy.

Real-space Mapping of Surface Trap States in CIGSe Nanocrystals using 4D Electron Microscopy

KAUST Repository

Bose, Riya

2016-05-26

Surface trap states in semiconductor copper indium gallium selenide nanocrystals (NCs) which serve as undesirable channels for non-radiative carrier recombination, remain a great challenge impeding the development of solar and optoelectronics devices based on these NCs. In order to design efficient passivation techniques to minimize these trap states, a precise knowledge about the charge carrier dynamics on the NCs surface is essential. However, selective mapping of surface traps requires capabilities beyond the reach of conventional laser spectroscopy and static electron microscopy; it can only be accessed by using a one-of-a-kind, second-generation four-dimensional scanning ultrafast electron microscope (4D S-UEM) with sub-picosecond temporal and nanometer spatial resolutions. Here, we precisely map the surface charge carrier dynamics of copper indium gallium selenide NCs before and after surface passivation in real space and time using S-UEM. The time-resolved snapshots clearly demonstrate that the density of the trap states is significantly reduced after zinc sulfide (ZnS) shelling. Furthermore, removal of trap states and elongation of carrier lifetime are confirmed by the increased photocurrent of the self-biased photodetector fabricated using the shelled NCs.

Real-space Mapping of Surface Trap States in CIGSe Nanocrystals using 4D Electron Microscopy

KAUST Repository

Bose, Riya; Bera, Ashok; Parida, Manas R.; Adhikari, Aniruddha; Shaheen, Basamat; Alarousu, Erkki; Sun, Jingya; Wu, Tao; Bakr, Osman; Mohammed, Omar F.

2016-01-01

Surface trap states in semiconductor copper indium gallium selenide nanocrystals (NCs) which serve as undesirable channels for non-radiative carrier recombination, remain a great challenge impeding the development of solar and optoelectronics devices based on these NCs. In order to design efficient passivation techniques to minimize these trap states, a precise knowledge about the charge carrier dynamics on the NCs surface is essential. However, selective mapping of surface traps requires capabilities beyond the reach of conventional laser spectroscopy and static electron microscopy; it can only be accessed by using a one-of-a-kind, second-generation four-dimensional scanning ultrafast electron microscope (4D S-UEM) with sub-picosecond temporal and nanometer spatial resolutions. Here, we precisely map the surface charge carrier dynamics of copper indium gallium selenide NCs before and after surface passivation in real space and time using S-UEM. The time-resolved snapshots clearly demonstrate that the density of the trap states is significantly reduced after zinc sulfide (ZnS) shelling. Furthermore, removal of trap states and elongation of carrier lifetime are confirmed by the increased photocurrent of the self-biased photodetector fabricated using the shelled NCs.

Pumped helium system for cooling positron and electron traps to 1.2 K

CERN Document Server

Wrubel, J; Kolthammer, W S; Larochelle, P; McConnell, R; Richerme, P; Grzonka, D; Oelert, W; Sefzick, T; Zielinski, M; Borbely, J S; George, M C; Hessels, E A; Storry, C H; Weel, M; Mullers, A; Walz, J; Speck, A

2011-01-01

Extremely precise tests of fundamental particle symmetries should be possible via laser spectroscopy of trapped antihydrogen ((H) over bar) atoms. (H) over bar atoms that can be trapped must have an energy in temperature units that is below 0.5 K-the energy depth of the deepest magnetic traps that can currently be constructed with high currents and superconducting technology. The number of atoms in a Boltzmann distribution with energies lower than this trap depth depends sharply upon the temperature of the thermal distribution. For example, ten times more atoms with energies low enough to be trapped are in a thermal distribution at a temperature of 1.2 K than for a temperature of 4.2 K. To date, (H) over bar atoms have only been produced within traps whose electrode temperature is 4.2 K or higher. A lower temperature apparatus is desirable if usable numbers of atoms that can be trapped are to eventually be produced. This report is about the pumped helium apparatus that cooled the trap electrodes of an (H) ove...

Project Closeout Report Francium trapping facility at Triumf

Energy Technology Data Exchange (ETDEWEB)

Orozco, Luis A [Univ. of Maryland, College Park, MD (United States)

2014-09-30

This is a report of the construction of a Francium Trapping Facility (FTF) at the Isotope Separator and Accelerator (ISAC) of TRIUMF in Vancouver, Canada, where the Francium Parity Non Conservation (FrPNC) international collaboration has its home. This facility will be used to study fundamental symmetries with high-resolution atomic spectroscopy. The primary scientific objective of the program is a measurement of the anapole moment of francium in a chain of isotopes by observing the parity violation induced by the weak interaction. The anapole moment of francium and associated signal are expected to be ten times larger than in cesium, the only element in which an anapole moment has been observed. The measurement will provide crucial information for better understanding weak hadronic interactions in the context of Quantum Chromodynamics (QCD). The methodology combines nuclear and particle physics techniques for the production of francium with precision measurements based on laser cooling and trapping and microwave spectroscopy. The program builds on an initial series of atomic spectroscopy measurements of the nuclear structure of francium, based on isotope shifts and hyperfine anomalies, before conducting the anapole moment measurements, these measurements performed during commissioning runs help understand the atomic and nuclear structure of Fr.

Cold molecules: formation, trapping and spectroscopy. - Piling up of cesium dimers in a quadrupolar magnetic trap. - Spectroscopy by lack of photo-association; Molecules froides: formation, piegeage et spectroscopie. - Accumulation de dimeres de cesium dans un piege quadrupolaire magnetique. - Spectroscopie par frustration de photoassociation

Energy Technology Data Exchange (ETDEWEB)

Vanhaecke, N

2003-10-15

This thesis deals with the study of cold molecules obtained through the cold atom photo-association technique. Our study is focused both on manipulating external degrees of freedom of these Cs{sub 2} molecules and on studying their internal interactions. A quadrupolar magnetic trap of about 2.10{sup 5} cold Cs{sub 2} molecules is demonstrated. The trap lifetime is on the order of 600 ms, mainly limited by the background gas pressure. The trapped molecules are identified, which allows the determination of the trapped molecule cloud temperature, which is about 35 {mu}K. A dipolar trap is set up by the use of a focused CO{sub 2} laser beam. Moreover, this thesis describes a two-photon photo-association spectroscopy. We report the first study of two-photon photo-association line shapes, which exhibit typical Fano profiles. Taking advantage of the detailed understanding of these line shapes, we measure over one hundred high-lying level energies with an accuracy on the order of 10 MHz. Then we interpret theoretically these energies. The huge hyperfine structure of the Cesium atom binds us to solve a coupled channel Schroedinger equation for internuclear distances above 15 a{sub 0}. Hence we use an asymptotic theory to fit the potential parameters of the Cs{sub 2} dimer. We adjust those parameters by the mean of both evolutionary strategies and deterministic optimum seeking. This is followed by a careful statistics study, which leads to a very accurate determination of the Vander Waals coefficient. Moreover we report the first experimental determination of the exchange interaction amplitude. (author)

Ultrafast Carrier Trapping of a Metal-Doped Titanium Dioxide Semiconductor Revealed by Femtosecond Transient Absorption Spectroscopy

KAUST Repository

Sun, Jingya; Yang, Yang; Khan, Jafar I.; Alarousu, Erkki; Guo, Zaibing; Zhang, Xixiang; Zhang, Qiang; Mohammed, Omar F.

2014-01-01

We explored for the first time the ultrafast carrier trapping of a metal-doped titanium dioxide (TiO2) semiconductor using broad-band transient absorption (TA) spectroscopy with 120 fs temporal resolution. Titanium dioxide was successfully doped layer-by-layer with two metal ions, namely tungsten and cobalt. The time-resolved data demonstrate clearly that the carrier trapping time decreases progressively as the doping concentration increases. A global-fitting procedure for the carrier trapping suggests the appearance of two time components: a fast one that is directly associated with carrier trapping to the defect state in the vicinity of the conduction band and a slow one that is attributed to carrier trapping to the deep-level state from the conduction band. With a relatively long doping deposition time on the order of 30 s, a carrier lifetime of about 1 ps is obtained. To confirm that the measured ultrafast carrier dynamics are associated with electron trapping by metal doping, we explored the carrier dynamics of undoped TiO2. The findings reported here may be useful for the implementation of high-speed optoelectronic applications and fast switching devices.

Ultrafast Carrier Trapping of a Metal-Doped Titanium Dioxide Semiconductor Revealed by Femtosecond Transient Absorption Spectroscopy

KAUST Repository

Sun, Jingya

2014-06-11

We explored for the first time the ultrafast carrier trapping of a metal-doped titanium dioxide (TiO2) semiconductor using broad-band transient absorption (TA) spectroscopy with 120 fs temporal resolution. Titanium dioxide was successfully doped layer-by-layer with two metal ions, namely tungsten and cobalt. The time-resolved data demonstrate clearly that the carrier trapping time decreases progressively as the doping concentration increases. A global-fitting procedure for the carrier trapping suggests the appearance of two time components: a fast one that is directly associated with carrier trapping to the defect state in the vicinity of the conduction band and a slow one that is attributed to carrier trapping to the deep-level state from the conduction band. With a relatively long doping deposition time on the order of 30 s, a carrier lifetime of about 1 ps is obtained. To confirm that the measured ultrafast carrier dynamics are associated with electron trapping by metal doping, we explored the carrier dynamics of undoped TiO2. The findings reported here may be useful for the implementation of high-speed optoelectronic applications and fast switching devices.

Investigation on H-containing shallow trap of hydrogenated TiO2 with in situ Fourier transform infrared diffuse reflection spectroscopy.

Science.gov (United States)

Han, Bing; Hang Hu, Yun

2017-07-28

A novel technique, high temperature high pressure in situ Fourier transform infrared diffuse reflection spectroscopy, was successfully used to investigate the formation and stability of shallow trap states in P25 TiO 2 nanoparticles. Two types of shallow traps (with and without H atoms) were identified. The H-containing shallow trap can be easily generated by heating in H 2 atmosphere. However, the trap is unstable in vacuum at 600 °C. In contrast, the H-free shallow trap, which can be formed by heating in vacuum, is stable even at 600 °C. The energy gaps between shallow trap states and the conduction band are 0.09 eV for H-containing shallow trap and 0.13 eV for H-free shallow trap, indicating that the H-containing shallow trap state is closer to the conduction band than that without H.

Computer Assisted Instruction (Cain) For Nuclear Magnetic Resonance Spectroscopy

International Nuclear Information System (INIS)

Jaturonrusmee, Wasna; Arthonvorakul, Areerat; Assateranuwat, Adisorn

2005-10-01

A computer assisted instruction program for nuclear magnetic resonance spectroscopy was developed by using Author ware 5.0, Adobe Image Styler 1.0, Adobe Photo shop 7.0 and Flash MX. The contents included the basic theory of 1H and 13C nuclear magnetic resonance (NMR) spectroscopy, the instrumentation of NMR spectroscopy, the two dimensional (2D) NMR spectroscopy and the interpretation of NMR spectra. The program was also provided examples, and exercises, with emphasis on NMR spectra interpretation to determine the structure of unknown compounds and solutions for self study. The questionnaire from students showed that they were very satisfied with the software

High-precision multiband spectroscopy of ultracold fermions in a nonseparable optical lattice

Science.gov (United States)

Fläschner, Nick; Tarnowski, Matthias; Rem, Benno S.; Vogel, Dominik; Sengstock, Klaus; Weitenberg, Christof

2018-05-01

Spectroscopic tools are fundamental for the understanding of complex quantum systems. Here, we demonstrate high-precision multiband spectroscopy in a graphenelike lattice using ultracold fermionic atoms. From the measured band structure, we characterize the underlying lattice potential with a relative error of 1.2 ×10-3 . Such a precise characterization of complex lattice potentials is an important step towards precision measurements of quantum many-body systems. Furthermore, we explain the excitation strengths into different bands with a model and experimentally study their dependency on the symmetry of the perturbation operator. This insight suggests the excitation strengths as a suitable observable for interaction effects on the eigenstates.

Use of spin traps to detect superoxide production in living cells by electron paramagnetic resonance (EPR) spectroscopy.

Science.gov (United States)

Abbas, Kahina; Babić, Nikola; Peyrot, Fabienne

2016-10-15

Detection of superoxide produced by living cells has been an on-going challenge in biology for over forty years. Various methods have been proposed to address this issue, among which spin trapping with cyclic nitrones coupled to EPR spectroscopy, the gold standard for detection of radicals. This technique is based on the nucleophilic addition of superoxide to a diamagnetic cyclic nitrone, referred to as the spin trap, and the formation of a spin adduct, i.e. a persistent radical with a characteristic EPR spectrum. The first application of spin trapping to living cells dates back 1979. Since then, considerable improvements of the method have been achieved both in the structures of the spin traps, the EPR methodology, and the design of the experiments including appropriate controls. Here, we will concentrate on technical aspects of the spin trapping/EPR technique, delineating recent breakthroughs, inherent limitations, and potential artifacts. Copyright © 2016 Elsevier Inc. All rights reserved.

Laser spectroscopy with an electrostatic ConeTrap

Energy Technology Data Exchange (ETDEWEB)

Kelly, S., E-mail: sam.kelly@postgrad.manchester.ac.uk; Campbell, P. [University of Manchester, Nuclear Physics Group, Schuster Laboratory, Brunswick Street (United Kingdom); Cheal, B., E-mail: Bradley.Cheal@Liverpool.ac.uk [University of Liverpool, Oliver Lodge Laboratory (United Kingdom); Eronen, T.; Geldhof, S.; Jokinen, A.; Moore, I. D.; Penttilä, H.; Pohjalainen, I.; Rinta-Antila, S.; Sonnenschein, V.; Voss, A. [JYFL, University of Jyväskylä (Finland)

2017-11-15

A compact electrostatic trap has been designed and installed as part of the recent upgrades to the IGISOL IV facility. The ConeTrap provides an in vacuo optical pumping site for low energy (800 eV) ionic ensembles available for interaction periods of 10-100 ms. At present, 6.7(3) % of injected mass A=98 ions can be trapped, stored for 5 ms, extracted and transported to a laser-ion interaction region. This fraction represents those ions for which no perturbation to total energy or energy spread is observed. Proposed enhancements to the trap are designed to improve the trapping efficiency by up to a factor of 5. Differential pumping and reduction in background pressure below the present 10{sup −6} mbar will extend storage times beyond 100 ms.

Freeze-quench (57)Fe-Mössbauer spectroscopy: trapping reactive intermediates.

Science.gov (United States)

Krebs, Carsten; Bollinger, J Martin

2009-01-01

(57)Fe-Mössbauer spectroscopy is a method that probes transitions between the nuclear ground state (I=1/2) and the first nuclear excited state (I=3/2). This technique provides detailed information about the chemical environment and electronic structure of iron. Therefore, it has played an important role in studies of the numerous iron-containing proteins and enzymes. In conjunction with the freeze-quench method, (57)Fe-Mössbauer spectroscopy allows for monitoring changes of the iron site(s) during a biochemical reaction. This approach is particularly powerful for detection and characterization of reactive intermediates. Comparison of experimentally determined Mössbauer parameters to those predicted by density functional theory for hypothetical model structures can then provide detailed insight into the structures of reactive intermediates. We have recently used this methodology to study the reactions of various mononuclear non-heme-iron enzymes by trapping and characterizing several Fe(IV)-oxo reaction intermediates. In this article, we summarize these findings and demonstrate the potential of the method. © Springer Science+Business Media B.V. 2009

Alkali Earth Ion Spectroscopy in Preparation of a Weinberg Angle Measurement

NARCIS (Netherlands)

Valappol, Nivedya; Dijck, Elwin; Hofsteenge, Aswin; Mohanty, Amita; Willmann, Lorenz; Jungmann, Klaus-Peter

2017-01-01

Through precision spectroscopy on Ba+ ions we determine precisely the 6s2S1/2 - 6p2P1/2, 6p2P1/2 - 5d2D3/2, 6s2S1/2 - 5d2D3/2 transition frequencies. In these experiments we employ laser-cooled single trapped ions. The optical frequencies are controlled by a frequency comb and I2 line locked laser

Laser Spectroscopy : XII International Conference

CERN Document Server

Allegrini, Maria; Sasso, Antonio

1996-01-01

This text includes all the recent advances in the field of laser spectroscopy. Major results span from the control of matter by electromagnetic fields (trapping and coding) to high precision measurements on simple atomic systems and to quantum optics with single atoms. It includes a report of the Bose-Einstein condensation achieved by laser-cooling of rubidium atoms. Achievements in the technology of tunable sources, in particular of miniaturized solid state devices, are also reported. Most recent advances in molecular spectroscopy are illustrated with emphasis on "cooled" spectra, clusters and high accuracy frequency references. Topics such as atomic interferometry and microcavity quantum optics are also covered.

High precision spectroscopy of pionic and antiprotonic atoms; Spectroscopie de precision des atomes pioniques et antiprotoniques

Energy Technology Data Exchange (ETDEWEB)

El-Khoury, P

1998-04-15

The study of exotic atoms, in which an orbiting electron of a normal atom is replaced by a negatively charged particle ({pi}{sup -}, {mu}{sup -}, p, {kappa}{sup -}, {sigma}{sup -},...) may provide information on the orbiting particle and the atomic nucleus, as well as on their interaction. In this work, we were interested in pionic atoms ({pi}{sup -14} N) on the one hand in order to determine the pion mass with high accuracy (4 ppm), and on the other hand in antiprotonic atoms (pp-bar) in order to study the strong nucleon-antinucleon interaction at threshold. In this respect, a high-resolution crystal spectrometer was coupled to a cyclotron trap which provides a high stop density for particles in gas targets at low pressure. Using curved crystals, an extended X-ray source could be imaged onto the detector. Charge-Coupled Devices were used as position sensitive detectors in order to measure the Bragg angle of the transition to a high precision. The use of gas targets resolved the ambiguity owing to the number of K electrons for the value of the pion mass, and, for the first time, strong interaction shift and broadening of the 2p level in antiprotonic hydrogen were measured directly. (author)

Revisiting the role of trap-assisted-tunneling process on current-voltage characteristics in tunnel field-effect transistors

Science.gov (United States)

Omura, Yasuhisa; Mori, Yoshiaki; Sato, Shingo; Mallik, Abhijit

2018-04-01

This paper discusses the role of trap-assisted-tunneling process in controlling the ON- and OFF-state current levels and its impacts on the current-voltage characteristics of a tunnel field-effect transistor. Significant impacts of high-density traps in the source region are observed that are discussed in detail. With regard to recent studies on isoelectronic traps, it has been discovered that deep level density must be minimized to suppress the OFF-state leakage current, as is well known, whereas shallow levels can be utilized to control the ON-state current level. A possible mechanism is discussed based on simulation results.

Measurement and simulation of the pressure ratio between the two traps of double Penning trap mass spectrometers

International Nuclear Information System (INIS)

Neidherr, D.; Blaum, K.; Block, M.; Ferrer, R.; Herfurth, F.; Ketelaer, J.; Nagy, Sz.; Weber, C.

2008-01-01

Penning traps are ideal tools to perform high-precision mass measurements. For this purpose the cyclotron frequency of the stored charged particles is measured. In case of on-line mass measurements of short-lived nuclides produced at radioactive beam facilities the ions get in general first prepared and cooled by buffer-gas collisions in a preparation trap to reduce their motional amplitudes and are then transported to a precision trap for the cyclotron frequency determination. In modern Penning trap mass spectrometers both traps are placed in the homogeneous region of one superconducting magnet to optimize the transport efficiency. Because the gas pressure inside the precision trap has to be very low in order to minimize the damping of the ion motion caused by collisions with rest gas molecules during the frequency determination, a pumping barrier is installed between both traps. To predict the pressure difference between the two traps in the region of molecular gas flow the motion of each particle can be simulated without consideration of the other particles. Thus, it is possible to calculate the transit probability through a tube of a given geometry. The results are compared with experimentally obtained pressure differences.

Photoionization and cold collision studies using trapped atoms

International Nuclear Information System (INIS)

Gould, P.L.

1996-01-01

The authors have used laser cooling and trapping techniques to investigate photoionization and cold collisions. With laser-trapped Rb, they have measured the photoionization cross section from the first excited (5P) level by observing the photoionization-induced loss rate of neutral atoms from the trap. This technique has the advantage that it directly measures the photoionization rate per atom. Knowing the ionizing laser intensity and the excited-state fraction, the measured loss rate gives the absolute cross section. Using this technique, the Rb 5P photoionization cross section at ∼400 nm has been determined with an uncertainty of 9%. The authors are currently attempting to extend this method to the 5D level. Using time-ordered pulses of diode-laser light (similar to the STIRAP technique), they have performed very efficient two-photon excitation of trapped Rb atoms to 5D. Finally, they will present results from a recent collaboration which combines measurements form conventional molecular spectroscopy (single photon and double resonance) with photoassociation collisions of ultracold Na atoms to yield a precise (≤1 ppm) value for the dissociation energy of the X Σ g+ ground state of the Na 2 molecule

Force-detected nanoscale absorption spectroscopy in water at room temperature using an optical trap

Science.gov (United States)

Parobek, Alexander; Black, Jacob W.; Kamenetska, Maria; Ganim, Ziad

2018-04-01

Measuring absorption spectra of single molecules presents a fundamental challenge for standard transmission-based instruments because of the inherently low signal relative to the large background of the excitation source. Here we demonstrate a new approach for performing absorption spectroscopy in solution using a force measurement to read out optical excitation at the nanoscale. The photoinduced force between model chromophores and an optically trapped gold nanoshell has been measured in water at room temperature. This photoinduced force is characterized as a function of wavelength to yield the force spectrum, which is shown to be correlated to the absorption spectrum for four model systems. The instrument constructed for these measurements combines an optical tweezer with frequency domain absorption spectroscopy over the 400-800 nm range. These measurements provide proof-of-principle experiments for force-detected nanoscale spectroscopies that operate under ambient chemical conditions.

Precision determination of pion mass using X-ray CCD spectroscopy

CERN Document Server

Nelms, N; Augsburger, M A; Borchert, G; Chatellard, D; Daum, M; Egger, J P; Gotta, D; Hauser, P; Indelicato, P J; Jeannet, E; Kirch, K; Schult, O W B; Siems, T; Simons, L M; Wells, A

2002-01-01

An experiment is described which aims to determine the charged pion mass to 1 ppm or better, from which a new determination of the upper limit of the muon neutrino mass is anticipated. The experimental approach uses a high-intensity negative pion beam (produced at the PSI 590 MeV proton cyclotron), injected into a cyclotron trap and stopped inside a gas-filled target chamber, to form highly excited exotic atoms of pionic nitrogen and muonic oxygen. The energy of photons, emitted during de-excitation, is directly proportional to the mass of the pion or muon. These soft X-ray emission spectra are measured using a high-precision crystal spectrometer, with an array of six, high quantum efficiency X-ray position resolving CCDs at the focus. To achieve sub-ppm accuracy, simultaneous calibration of the pionic nitrogen line is provided by measurement of an adjacent muonic oxygen line, whose energy is known to 0.3 ppm. The high precision of the experiment offers a new opportunity to determine the pion mass to the leve...

Tunable potential well for plasmonic trapping of metallic particles by bowtie nano-apertures.

Science.gov (United States)

Lu, Yu; Du, Guangqing; Chen, Feng; Yang, Qing; Bian, Hao; Yong, Jiale; Hou, Xun

2016-09-26

In this paper, the tunable optical trapping dependence on wavelength of incident beam is theoretically investigated based on numerical simulations. The Monte Carlo method is taken into account for exploring the trapping characteristics such as average deviation and number distribution histogram of nanoparticles. It is revealed that both the width and the depth of potential well for trapping particles can be flexibly adjusted by tuning the wavelength of the incident beam. In addition, incident wavelengths for the deepest potential well and for the strongest stiffness at bottom are separated. These phenomena are explained as the strong plasmon coupling between tweezers and metallic nanoparticles. In addition, required trapping fluence and particles' distributions show distinctive properties through carefully modifying the incident wavelengths from 1280 nm to 1300 nm. Trapping with lowest laser fluence can be realized with 1280 nm laser and trapping with highest precision can be realized with 1300 nm laser. This work will provide theoretical support for advancing the manipulation of metallic particles and related applications such as single-molecule fluorescence and surface enhanced Raman spectroscopy.

Derivation of the tunnelling exchange time for the model of trap-assisted tunnelling

International Nuclear Information System (INIS)

Racko, J.; Ballo, P.; Benko, P.; Harmatha, L.; Grmanova, A.; Breza, J.

2014-01-01

We present derivation of the tunnelling exchange times that play the key role in the model of trap assisted tunnelling (TAT) considering the electron and hole exchange processes between the trapping centre lying in the forbidden band of the semiconductor and the conduction band, valence band or a metal. All exchange processes are quantitatively described by respective exchange times. The reciprocal values of these exchange times represent the frequency with which the exchange processes contribute to the probability of occupation of the trap by free charge carriers. The crucial problem in any model of TAT is the calculation of the occupation probability. In our approach this probability is expressed in terms of only thermal and tunnelling exchange times. The concept of tunnelling exchange times presents a dominant contribution to our model of TAT. The new approach allows to simply calculate the probability of occupation of the trapping centre by a free charge carrier and subsequently to get the thermal and tunnelling generation-recombination rates occurring in the continuity equations. This is why the TAT model based on thermal and tunnelling exchange times is suitable for simulating the electrical properties of semiconductor nanostructures in which quantum mechanical phenomena play a key role. (authors)

Precision spectroscopy of molecular hydrogen ions : Towards frequency metrology of particle masses

NARCIS (Netherlands)

Roth, B.; Koelemeij, J.; Schiller, S.; Hilico, L.; Karr, Jean Philippe; Korobov, V.I.; Bakalov, D.

2008-01-01

We describe the current status of high-precision ab initio calculations of the spectra of molecular hydrogen ions (H2+ and HD+) and of two experiments for vibrational spectroscopy. The perspectives for a comparison between theory and experiment at a level of 1 part in 109 are considered.

Towards a precise measurement of atomic parity violation in a single Ra{sup +} ion

Energy Technology Data Exchange (ETDEWEB)

Nunez Portela, M., E-mail: nunez@kvi.nl; Berg, J. E. van den; Bekker, H.; Boell, O.; Dijck, E. A.; Giri, G. S.; Hoekstra, S.; Jungmann, K.; Mohanty, A.; Onderwater, C. J. G.; Santra, B.; Schlesser, S.; Timmermans, R. G. E.; Versolato, O. O.; Wansbeek, L. W.; Willmann, L.; Wilschut, H. W. [Kernfysisch Versneller Instituut (KVI) (Netherlands)

2013-03-15

A single trapped Ra{sup + } (Z = 88) ion provides a very promising route towards a most precise measurement of Atomic Parity Violation (APV), since APV effects grow faster than Z{sup 3}. This experiment promises the best determination of the electroweak coupling constant at the lowest accessible energies. Such a measurement provides a sensitive test of the Standard Model in particle physics. At the present stage of the experiment, we focus on trapping and laser cooling stable Ba{sup + } ions as a precursor for radioactive Ra{sup + }. Online laser spectroscopy of the isotopes {sup 209 - 214}Ra{sup + } in a linear Paul trap has provided information on transition wavelengths, fine and hyperfine structures and excited state lifetimes as test of atomic structure calculations. Additionaly, a single trapped Ra{sup + } ion could function as a very stable clock.

Towards a precise measurement of atomic parity violation in a single Ra+ ion

International Nuclear Information System (INIS)

Nuñez Portela, M.; Berg, J. E. van den; Bekker, H.; Böll, O.; Dijck, E. A.; Giri, G. S.; Hoekstra, S.; Jungmann, K.; Mohanty, A.; Onderwater, C. J. G.; Santra, B.; Schlesser, S.; Timmermans, R. G. E.; Versolato, O. O.; Wansbeek, L. W.; Willmann, L.; Wilschut, H. W.

2013-01-01

A single trapped Ra  +  (Z = 88) ion provides a very promising route towards a most precise measurement of Atomic Parity Violation (APV), since APV effects grow faster than Z 3 . This experiment promises the best determination of the electroweak coupling constant at the lowest accessible energies. Such a measurement provides a sensitive test of the Standard Model in particle physics. At the present stage of the experiment, we focus on trapping and laser cooling stable Ba  +  ions as a precursor for radioactive Ra  +  . Online laser spectroscopy of the isotopes 209 − 214 Ra  +  in a linear Paul trap has provided information on transition wavelengths, fine and hyperfine structures and excited state lifetimes as test of atomic structure calculations. Additionaly, a single trapped Ra  +  ion could function as a very stable clock.

Conception of PIPERADE: A high-capacity Penning-trap mass separator for high isobaric contamination at DESIR

Energy Technology Data Exchange (ETDEWEB)

Minaya Ramirez, E., E-mail: minaya@ipno.in2p3.fr [Max-Planck-Institut für Kernphysik, 69117 Heidelberg (Germany); Alfaurt, P.; Aouadi, M.; Ascher, P.; Blank, B. [Centre d’Etudes Nucléaires de Bordeaux-Gradignan (France); Blaum, K. [Max-Planck-Institut für Kernphysik, 69117 Heidelberg (Germany); Cam, J.-F. [Laboratoire de Physique Corpusculaire, Caen (France); Chauveau, P. [Grand Accélérateur National d’Ions Lourds CEA/DSM-CNRS-IN2P3, Caen (France); Daudin, L. [Centre d’Etudes Nucléaires de Bordeaux-Gradignan (France); Delahaye, P. [Grand Accélérateur National d’Ions Lourds CEA/DSM-CNRS-IN2P3, Caen (France); Delalee, F. [Centre d’Etudes Nucléaires de Bordeaux-Gradignan (France); Dupré, P. [Centre de Sciences Nucléaires et de Sciences de la Matière, Orsay (France); El Abbeir, S.; Gerbaux, M.; Grévy, S.; Guérin, H. [Centre d’Etudes Nucléaires de Bordeaux-Gradignan (France); Lunney, D. [Centre de Sciences Nucléaires et de Sciences de la Matière, Orsay (France); Metz, F. [Max-Planck-Institut für Kernphysik, 69117 Heidelberg (Germany); Naimi, S. [Riken, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Perrot, L. [Institut de Physique Nucléaire, Orsay (France); and others

2016-06-01

The DESIR (decay, excitation and storage of radioactive ions) facility at GANIL-SPIRAL2 will receive a large variety of exotic nuclei at low energy (up to 60 keV) with high intensities. However, the production methods of radioactive beams are non selective, limiting the purity of the beams of interest. Moreover, the high precision needed for nuclear structure and astrophysics studies using beta decay spectroscopy, laser spectroscopy and trap-based experiments at DESIR requires highly pure samples of exotic nuclei. The aim of the double-Pennig-trap mass separator PIPERADE is to deliver large and very pure samples of exotic nuclei to the different experiments in DESIR. New excitation schemes and a large inner diameter of the first trap will mitigate space charge effects to attempt trapping of up to 10{sup 5} ions per pulse. The purification cycle will be performed in a few milliseconds so that short-lived nuclei can be purified. To extract the nuclides of interest from the large amount of isobaric contaminants, a resolving power of 10{sup 5} is mandatory. Afterwards the ions of interest will be accumulated in the second trap until they constitute a sufficiently pure sample for the measurements. The status of the project is presented.

Calibration of the ISOLDE acceleration voltage using a high-precision voltage divider and applying collinear fast beam laser spectroscopy

CERN Document Server

Krieger, A.; Catherall, R.; Hochschulz, F.; Kramer, J.; Neugart, R.; Rosendahl, S.; Schipper, J.; Siesling, E.; Weinheimer, Ch.; Yordanov, D.T.; Nortershauser, W.

2011-01-01

A high-voltage divider with accuracy at the ppm level and collinear laser spectroscopy were used to calibrate the highvoltage installation at the radioactive ion beam facility ISOLDE at CERN. The accurate knowledge of this voltage is particularly important for collinear laser spectroscopy measurements. Beam velocity measurements using frequencycomb based collinear laser spectroscopy agree with the new calibration. Applying this, one obtains consistent results for isotope shifts of stable magnesium isotopes measured using collinear spectroscopy and laser spectroscopy on laser-cooled ions in a trap. The long-term stability and the transient behavior during recovery from a voltage dropout were investigated for the different power supplies currently applied at ISOLDE.

Antihydrogen atom formation in a CUSP trap towards spin polarized beams

Energy Technology Data Exchange (ETDEWEB)

Kuroda, N., E-mail: kuroda@radphys4.c.u-tokyo.ac.jp [University of Tokyo, Graduate School of Arts and Sciences (Japan); Enomoto, Y. [RIKEN Advanced Science Institute (Japan); Michishio, K. [Tokyo University of Science, Department of Physics (Japan); Kim, C. H. [University of Tokyo, Graduate School of Arts and Sciences (Japan); Higaki, H. [Hiroshima University, Graduate School of Advanced Science of Matter (Japan); Nagata, Y.; Kanai, Y. [RIKEN Advanced Science Institute (Japan); Torii, H. A. [University of Tokyo, Graduate School of Arts and Sciences (Japan); Corradini, M.; Leali, M.; Lodi-Rizzini, E.; Venturelli, L.; Zurlo, N. [Universita di Brescia and Instituto Nazionale di Fisica Nucleare, Dipartimento di Chimica e Fisica per l' Ingegneria e per i Materiali (Italy); Fujii, K.; Ohtsuka, M.; Tanaka, K. [University of Tokyo, Graduate School of Arts and Sciences (Japan); Imao, H. [RIKEN Nishina Center for Accelerator-Based Science (Japan); Nagashima, Y. [Tokyo University of Science, Department of Physics (Japan); Matsuda, Y. [University of Tokyo, Graduate School of Arts and Sciences (Japan); Juhasz, B. [Stefan Meyer Institut fuer Subatomare Physik (Austria); and others

2012-12-15

The ASACUSA collaboration has been making a path to realize high precision microwave spectroscopy of ground-state hyperfine transitions of antihydrogen atom in flight for stringent test of the CPT symmetry. For this purpose, an efficient extraction of a spin polarized antihydrogen beam is essential. In 2010, we have succeeded in synthesizing our first cold antihydrogen atoms employing a CUSP trap. The CUSP trap confines antiprotons and positrons simultaneously with its axially symmetric magnetic field to form antihydrogen atoms. It is expected that antihydrogen atoms in the low-field-seeking states are preferentially focused along the cusp magnetic field axis whereas those in the high-field-seeking states are defocused, resulting in the formation of a spin-polarized antihydrogen beam.

UV Photodissociation Action Spectroscopy of Haloanilinium Ions in a Linear Quadrupole Ion Trap Mass Spectrometer

Science.gov (United States)

Hansen, Christopher S.; Kirk, Benjamin B.; Blanksby, Stephen J.; O'Hair, Richard. A. J.; Trevitt, Adam J.

2013-06-01

UV-vis photodissociation action spectroscopy is becoming increasingly prevalent because of advances in, and commercial availability of, ion trapping technologies and tunable laser sources. This study outlines in detail an instrumental arrangement, combining a commercial ion-trap mass spectrometer and tunable nanosecond pulsed laser source, for performing fully automated photodissociation action spectroscopy on gas-phase ions. The components of the instrumentation are outlined, including the optical and electronic interfacing, in addition to the control software for automating the experiment and performing online analysis of the spectra. To demonstrate the utility of this ensemble, the photodissociation action spectra of 4-chloroanilinium, 4-bromoanilinium, and 4-iodoanilinium cations are presented and discussed. Multiple photoproducts are detected in each case and the photoproduct yields are followed as a function of laser wavelength. It is shown that the wavelength-dependent partitioning of the halide loss, H loss, and NH3 loss channels can be broadly rationalized in terms of the relative carbon-halide bond dissociation energies and processes of energy redistribution. The photodissociation action spectrum of (phenyl)Ag2 + is compared with a literature spectrum as a further benchmark.

Detection of electron and hole traps in CdZnTe radiation detectors by thermoelectric emission spectroscopy and thermally stimulated conductivity

International Nuclear Information System (INIS)

Lee, E.Y.; Brunett, B.A.; Olsen, R.W.; Van Scyoc, J.M. III; Hermon, H.; James, R.B.

1998-01-01

The electrical properties of CdZnTe radiation detectors are largely determined by electron and hole traps in this material. The traps, in addition to degrading the detector performance, can function as dopants and determine the resistivity of the material. Thermoelectric emission spectroscopy and thermally stimulated conductivity are used to detect these traps in a commercially available spectrometer-grade CdZnTe detector, and the electrical resistivity is measured as a function of temperature. A deep electron trap having an energy of 695 meV and cross section of 8 x 10 -16 cm 2 is detected and three hole traps having energies of 70 ± 20 meV, 105 ± 30 meV and 694 ± 162 meV are detected. A simple model based on these traps explains quantitatively all the data, including the electrical properties at room temperature and also their temperature dependence

Atomic force microscope-assisted scanning tunneling spectroscopy under ambient conditions.

Science.gov (United States)

Vakhshouri, Amin; Hashimoto, Katsushi; Hirayama, Yoshiro

2014-12-01

We have developed a method of atomic force microscopy (AFM)-assisted scanning tunneling spectroscopy (STS) under ambient conditions. An AFM function is used for rapid access to a selected position prior to performing STS. The AFM feedback is further used to suppress vertical thermal drift of the tip-sample distance during spectroscopy, enabling flexible and stable spectroscopy measurements at room temperature. © The Author 2014. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Magneto optical trap recoil ion momentum spectroscopy: application to ion-atom collisions

International Nuclear Information System (INIS)

Blieck, J.

2008-10-01

87 Rb atoms have been cooled, trapped and prepared as targets for collision studies with 2 and 5 keV Na + projectiles. The physics studied deals with charge exchange processes. The active electron, which is generally the most peripheral electron of the atomic target, is transferred from the target onto the ionic projectile. The ionized target is called recoil ion. The technique used to study this physics is the MOTRIMS (Magneto Optical Trap Recoil Ion Momentum Spectroscopy) technique, which combines a magneto optical trap and a recoil ion momentum spectrometer. The spectrometer is used for the measurement of the recoil ions momentum, which gives access to all the information of the collision: the Q-value (which is the potential energy difference of the active electron on each particle) and the scattering angle of the projectile. The trap provides extremely cold targets to optimize the measurement of the momentum, and to release the latter from thermal motion. Through cinematically complete experiments, the MOTRIMS technique gives access to better resolutions on momentum measurements. Measurements of differential cross sections in initial and final capture states and in scattering angle have been done. Results obtained for differential cross sections in initial and final states show globally a good agreement with theory and an other experiment. Nevertheless, discrepancies with theory and this other experiment are shown for the measurements of doubly differential cross sections. These discrepancies are not understood yet. The particularity of the experimental setup designed and tested in this work, namely a low background noise, allows a great sensitivity to weak capture channels, and brings a technical and scientific gain compared with previous works. (author)

Improving accuracy and precision of ice core δD(CH4 analyses using methane pre-pyrolysis and hydrogen post-pyrolysis trapping and subsequent chromatographic separation

Directory of Open Access Journals (Sweden)

M. Bock

2014-07-01

Full Text Available Firn and polar ice cores offer the only direct palaeoatmospheric archive. Analyses of past greenhouse gas concentrations and their isotopic compositions in air bubbles in the ice can help to constrain changes in global biogeochemical cycles in the past. For the analysis of the hydrogen isotopic composition of methane (δD(CH4 or δ2H(CH4 0.5 to 1.5 kg of ice was hitherto used. Here we present a method to improve precision and reduce the sample amount for δD(CH4 measurements in (ice core air. Pre-concentrated methane is focused in front of a high temperature oven (pre-pyrolysis trapping, and molecular hydrogen formed by pyrolysis is trapped afterwards (post-pyrolysis trapping, both on a carbon-PLOT capillary at −196 °C. Argon, oxygen, nitrogen, carbon monoxide, unpyrolysed methane and krypton are trapped together with H2 and must be separated using a second short, cooled chromatographic column to ensure accurate results. Pre- and post-pyrolysis trapping largely removes the isotopic fractionation induced during chromatographic separation and results in a narrow peak in the mass spectrometer. Air standards can be measured with a precision better than 1‰. For polar ice samples from glacial periods, we estimate a precision of 2.3‰ for 350 g of ice (or roughly 30 mL – at standard temperature and pressure (STP – of air with 350 ppb of methane. This corresponds to recent tropospheric air samples (about 1900 ppb CH4 of about 6 mL (STP or about 500 pmol of pure CH4.

The Role of Trap-assisted Recombination in Luminescent Properties of Organometal Halide CH3NH3PbBr3 Perovskite Films and Quantum Dots

Science.gov (United States)

Zhang, Zhen-Yu; Wang, Hai-Yu; Zhang, Yan-Xia; Hao, Ya-Wei; Sun, Chun; Zhang, Yu; Gao, Bing-Rong; Chen, Qi-Dai; Sun, Hong-Bo

2016-06-01

Hybrid metal halide perovskites have been paid enormous attentions in photophysics research, whose excellent performances were attributed to their intriguing charge carriers proprieties. However, it still remains far from satisfaction in the comprehensive understanding of perovskite charge-transport properities, especially about trap-assisted recombination process. In this Letter, through time-resolved transient absorption (TA) and photoluminescence (PL) measurements, we provided a relative comprehensive investigation on the charge carriers recombination dynamics of CH3NH3PbBr3 (MAPbBr3) perovskite films and quantum dots (QDs), especially about trap-assisted recombination. It was found that the integral recombination mode of MAPbBr3 films was highly sensitive to the density distribution of generated charge carriers and trap states. Additional, Trap effects would be gradually weakened with elevated carrier densities. Furthermore, the trap-assisted recombination can be removed from MAPbBr3 QDs through its own surface passivation mechanism and this specialty may render the QDs as a new material in illuminating research. This work provides deeper physical insights into the dynamics processes of MAPbBr3 materials and paves a way toward more light-harvesting applications in future.

Precision Spectroscopy, Diode Lasers, and Optical Frequency Measurement Technology

Science.gov (United States)

Hollberg, Leo (Editor); Fox, Richard (Editor); Waltman, Steve (Editor); Robinson, Hugh

1998-01-01

This compilation is a selected set of reprints from the Optical Frequency Measurement Group of the Time and Frequency Division of the National Institute of Standards and Technology, and consists of work published between 1987 and 1997. The two main programs represented here are (1) development of tunable diode-laser technology for scientific applications and precision measurements, and (2) research toward the goal of realizing optical-frequency measurements and synthesis. The papers are organized chronologically in five, somewhat arbitrarily chosen categories: Diode Laser Technology, Tunable Laser Systems, Laser Spectroscopy, Optical Synthesis and Extended Wavelength Coverage, and Multi-Photon Interactions and Optical Coherences.

Precision Spectroscopy of Molecular Hydrogen and the Search for New Physics

Science.gov (United States)

Ubachs, Wim

2017-06-01

The hydrogen molecule is the smallest neutral chemical entity and a benchmark system of molecular spectroscopy. The comparison between highly accurate measurements of transition frequencies and level energies with quantum calculations including all known phenomena (relativistic, vacuum polarization and self energy) provides a tool to search for physical phenomena in the realm of the unknown: are there forces beyond the three included in the Standard Model of physics plus gravity [1], are there extra dimensions beyond the 3+1 describing space time [2] ? Comparison of laboratory wavelengths of transitions in hydrogen may be compared with the lines observed during the epoch of the early Universe to verify whether fundamental constants of Nature have varied over cosmological time [3]. These concepts, as well as the precision laboratory experiments and the astronomical observations used for such searches of new physics [4] will be discussed. [1] E.J. Salumbides, J.C.J. Koelemeij, J. Komasa, K. Pachucki, K.S.E. Eikema, W. Ubachs, Bounds on fifth forces from precision measurements on molecules, Phys. Rev. D87, 112008 (2013). [2] E.J. Salumbides, A.N. Schellekens, B. Gato-Rivera, W. Ubachs Constraints on extra dimensions from molecular spectroscopy, New. J. Phys. 17, 033015 (2015). [3] W. Ubachs, J. Bagdonaite, E.J. Salumbides, M.T. Murphy, L. Kaper, Search for a drifting proton-electron mass ratio from H_2, Rev. Mod. Phys. 88, 021003 (2016). [4] W. Ubachs, J.C.J. Koelemeij, K.S.E. Eikema, E.J. Salumbides, Physics beyond the Standard Model from hydrogen spectroscopy, J. Mol. Spectr. 320, 1 (2016).

Calibration of the ISOLDE acceleration voltage using a high-precision voltage divider and applying collinear fast beam laser spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Krieger, A., E-mail: kriegea@uni-mainz.d [Institut fuer Kernchemie, Johannes Gutenberg, Universitaet Mainz, Fritz-Strassmann-Weg 2, 55128 Mainz (Germany); Geppert, Ch. [Institut fuer Kernchemie, Johannes Gutenberg, Universitaet Mainz, Fritz-Strassmann-Weg 2, 55128 Mainz (Germany); GSI Helmholtzzentrum fuer Schwerionenforschung, 64291 Darmstadt (Germany); Catherall, R. [CERN, CH-1211 Geneve 23 (Switzerland); Hochschulz, F. [Institut fuer Kernphysik, Universitaet Muenster, 48149 Muenster (Germany); Kraemer, J.; Neugart, R. [Institut fuer Kernchemie, Johannes Gutenberg, Universitaet Mainz, Fritz-Strassmann-Weg 2, 55128 Mainz (Germany); Rosendahl, S. [Institut fuer Kernphysik, Universitaet Muenster, 48149 Muenster (Germany); Schipper, J.; Siesling, E. [CERN, CH-1211 Geneve 23 (Switzerland); Weinheimer, Ch. [Institut fuer Kernphysik, Universitaet Muenster, 48149 Muenster (Germany); Yordanov, D.T. [Max-Planck-Institut fuer Kernphysik, 69117 Heidelberg (Germany); Noertershaeuser, W. [Institut fuer Kernchemie, Johannes Gutenberg, Universitaet Mainz, Fritz-Strassmann-Weg 2, 55128 Mainz (Germany); GSI Helmholtzzentrum fuer Schwerionenforschung, 64291 Darmstadt (Germany)

2011-03-11

A high-voltage divider with accuracy at the ppm level and collinear laser spectroscopy were used to calibrate the high-voltage installation at the radioactive ion beam facility ISOLDE at CERN. The accurate knowledge of this voltage is particularly important for collinear laser spectroscopy measurements. Beam velocity measurements using frequency-comb based collinear laser spectroscopy agree with the new calibration. Applying this, one obtains consistent results for isotope shifts of stable magnesium isotopes measured using collinear spectroscopy and laser spectroscopy on laser-cooled ions in a trap. The long-term stability and the transient behavior during recovery from a voltage dropout were investigated for the different power supplies currently applied at ISOLDE.

Engineering Vibrationally Assisted Energy Transfer in a Trapped-Ion Quantum Simulator

Science.gov (United States)

Gorman, Dylan J.; Hemmerling, Boerge; Megidish, Eli; Moeller, Soenke A.; Schindler, Philipp; Sarovar, Mohan; Haeffner, Hartmut

2018-01-01

Many important chemical and biochemical processes in the condensed phase are notoriously difficult to simulate numerically. Often, this difficulty arises from the complexity of simulating dynamics resulting from coupling to structured, mesoscopic baths, for which no separation of time scales exists and statistical treatments fail. A prime example of such a process is vibrationally assisted charge or energy transfer. A quantum simulator, capable of implementing a realistic model of the system of interest, could provide insight into these processes in regimes where numerical treatments fail. We take a first step towards modeling such transfer processes using an ion-trap quantum simulator. By implementing a minimal model, we observe vibrationally assisted energy transport between the electronic states of a donor and an acceptor ion augmented by coupling the donor ion to its vibration. We tune our simulator into several parameter regimes and, in particular, investigate the transfer dynamics in the nonperturbative regime often found in biochemical situations.

A reservoir trap for antiprotons

CERN Document Server

Smorra, Christian; Franke, Kurt; Nagahama, Hiroki; Schneider, Georg; Higuchi, Takashi; Van Gorp, Simon; Blaum, Klaus; Matsuda, Yasuyuki; Quint, Wolfgang; Walz, Jochen; Yamazaki, Yasunori; Ulmer, Stefan

2015-01-01

We have developed techniques to extract arbitrary fractions of antiprotons from an accumulated reservoir, and to inject them into a Penning-trap system for high-precision measurements. In our trap-system antiproton storage times > 1.08 years are estimated. The device is fail-safe against power-cuts of up to 10 hours. This makes our planned comparisons of the fundamental properties of protons and antiprotons independent from accelerator cycles, and will enable us to perform experiments during long accelerator shutdown periods when background magnetic noise is low. The demonstrated scheme has the potential to be applied in many other precision Penning trap experiments dealing with exotic particles.

Deuterium trapping at vacancy clusters in electron/neutron-irradiated tungsten studied by positron annihilation spectroscopy

Science.gov (United States)

Toyama, T.; Ami, K.; Inoue, K.; Nagai, Y.; Sato, K.; Xu, Q.; Hatano, Y.

2018-02-01

Deuterium trapping at irradiation-induced defects in tungsten, a candidate material for plasma facing components in fusion reactors, was revealed by positron annihilation spectroscopy. Pure tungsten was electron-irradiated (8.5 MeV at ∼373 K and to a dose of ∼1 × 10-3 dpa) or neutron-irradiated (at 573 K to a dose of ∼0.3 dpa), followed by post-irradiation annealing at 573 K for 100 h in deuterium gas of ∼0.1 MPa. In both cases of electron- or neutron-irradiation, vacancy clusters were found by positron lifetime measurements. In addition, positron annihilation with deuterium electrons was demonstrated by coincidence Doppler broadening measurements, directly indicating deuterium trapping at vacancy-type defects. This is expected to cause significant increase in deuterium retention in irradiated-tungsten.

Demonstration of a Fast, Precise Propane Measurement Using Infrared Spectroscopy

Science.gov (United States)

Zahniser, M. S.; Roscioli, J. R.; Nelson, D. D.; Herndon, S. C.

2016-12-01

Propane is one of the primary components of emissions from natural gas extraction and processing activities. In addition to being an air pollutant, its ratio to other hydrocarbons such as methane and ethane can serve as a "fingerprint" of a particular facility or process, aiding in identifying emission sources. Quantifying propane has typically required laboratory analysis of flask samples, resulting in low temporal resolution and making plume-based measurements infeasible. Here we demonstrate fast (1-second), high precision (infrared spectroscopy at 2967 wavenumbers. In addition, we explore the impact of nearby water and ethane absorption lines on the accuracy and precision of the propane measurement. Finally, we discuss development of a dual-laser instrument capable of simultaneous measurements of methane, ethane, and propane (the C1-C3 compounds), all within a small spatial package that can be easily deployed aboard a mobile platform.

Spectroscopy, Manipulation and Trapping of Neutral Atoms, Molecules, and Other Particles Using Optical Nanofibers: A Review

Science.gov (United States)

Morrissey, Michael J.; Deasy, Kieran; Frawley, Mary; Kumar, Ravi; Prel, Eugen; Russell, Laura; Truong, Viet Giang; Chormaic, Síle Nic

2013-01-01

The use of tapered optical fibers, i.e., optical nanofibers, for spectroscopy and the detection of small numbers of particles, such as neutral atoms or molecules, has been gaining interest in recent years. In this review, we briefly introduce the optical nanofiber, its fabrication, and optical mode propagation within. We discuss recent progress on the integration of optical nanofibers into laser-cooled atom and vapor systems, paying particular attention to spectroscopy, cold atom cloud characterization, and optical trapping schemes. Next, a natural extension of this work to molecules is introduced. Finally, we consider several alternatives to optical nanofibers that display some advantages for specific applications. PMID:23945738

Compensation and trapping in CdZnTe radiation detectors studied by thermoelectric emission spectroscopy, thermally stimulated conductivity, and current-voltage measurements

International Nuclear Information System (INIS)

James, Ralph B.

2000-01-01

In today's commercially available counter-select-grade CdZnTe crystals for radiation detector applications, the thermal ionization energies of the traps and their types, whether electron or hole traps, were measured. The measurements were successfully done using thermoelectric emission spectroscopy (TEES) and thermally stimulated conductivity (TSC). For reliability, the electrical contacts to the sample were found to be very important and, instead of Au Schottky contacts, In Ohmic contacts had to be used. For the filling of the traps, photoexcitation was done at zero bias, at 20K and at wavelengths which gave the maximum bulk photoexcitation for the sample. Between the temperature range from 20 to 400 K, the TSC current was found to be on the order of ∼ 10,000 times or even larger than the TEES current, in agreement with theory, but only TEES could resolve the trap type and was sensitive to the deep traps. Large concentration of hole traps at 0.1 and 0.6 eV were observed and smaller contraction of electron traps at 0.4 eV was seen. These deep traps cause compensation in the material and also cause trapping that degrades the radiation detection measurement

Distinguishing bulk traps and interface states in deep-level transient spectroscopy

International Nuclear Information System (INIS)

Coelho, A V P; Adam, M C; Boudinov, H

2011-01-01

A new method for the distinction of discrete bulk deep levels and interface states related peaks in deep-level transient spectroscopy spectra is proposed. The measurement of two spectra using different reverse voltages while keeping pulse voltage fixed causes different peak maximum shifts in each case: for a reverse voltage modulus increase, a bulk deep-level related peak maximum will remain unchanged or shift towards lower temperatures while only interface states related peak maximum will be able to shift towards higher temperatures. This method has the advantage of being non-destructive and also works in the case of bulk traps with strong emission rate dependence on the electric field. Silicon MOS capacitors and proton implanted GaAs Schottky diodes were employed to experimentally test the method.

Recent trends in precision measurements of atomic and nuclear properties with lasers and ion traps

Science.gov (United States)

Block, Michael

2017-11-01

The X. international workshop on "Application of Lasers and Storage Devices in Atomic Nuclei Research" took place in Poznan in May 2016. It addressed the latest experimental and theoretical achievements in laser and ion trap-based investigations of radionuclides, highly charged ions and antiprotons. The precise determination of atomic and nuclear properties provides a stringent benchmark for theoretical models and eventually leads to a better understanding of the underlying fundamental interactions and symmetries. This article addresses some general trends in this field and highlights select recent achievements presented at the workshop. Many of these are covered in more detail within the individual contributions to this special issue of Hyperfine Interactions.

Recent trends in precision measurements of atomic and nuclear properties with lasers and ion traps

Energy Technology Data Exchange (ETDEWEB)

Block, Michael, E-mail: m.block@gsi.de [GSI Helmholtzzentrum für Schwerionenforschung GmbH (Germany)

2017-11-15

The X. international workshop on “Application of Lasers and Storage Devices in Atomic Nuclei Research” took place in Poznan in May 2016. It addressed the latest experimental and theoretical achievements in laser and ion trap-based investigations of radionuclides, highly charged ions and antiprotons. The precise determination of atomic and nuclear properties provides a stringent benchmark for theoretical models and eventually leads to a better understanding of the underlying fundamental interactions and symmetries. This article addresses some general trends in this field and highlights select recent achievements presented at the workshop. Many of these are covered in more detail within the individual contributions to this special issue of Hyperfine Interactions.

Persistent photocurrent and deep level traps in PLD-grown In-Ga-Zn-O thin films studied by thermally stimulated current spectroscopy

Science.gov (United States)

Wang, Buguo; Anders, Jason; Leedy, Kevin; Schuette, Michael; Look, David

2018-02-01

InGaZnO (IGZO) is a promising semiconductor material for thin-film transistors (TFTs) used in DC and RF switching applications, especially since it can be grown at low temperatures on a wide variety of substrates. Enhancement-mode TFTs based on IGZO thin films grown by pulsed laser deposition (PLD) have been recently fabricated and these transistors show excellent performance; however, compositional variations and defects can adversely affect film quality, especially in regard to electrical properties. In this study, we use thermally stimulated current (TSC) spectroscopy to characterize the electrical properties and the deep traps in PLD-grown IGZO thin films. It was found that the as-grown sample has a DC activation energy of 0.62 eV, and two major traps with activation energies at 0.16-0.26 eV and at 0.90 eV. However, a strong persistent photocurrent (PPC) sometimes exists in the as-grown sample, so we carry out post-growth annealing in an attempt to mitigate the effect. It was found that annealing in argon increases the conduction, produces more PPC and also makes more traps observable. Annealing in air makes the film more resistive, and removes PPC and all traps but one. This work demonstrates that current-based trap emission, such as that associated with the TSC, can effectively reveal electronic defects in highlyresistive semiconductor materials, especially those are not amenable to capacitance-based techniques, such as deeplevel transient spectroscopy (DLTS).

Near-infrared spectroscopy can reveal increases in brain activity related to animal-assisted therapy.

Science.gov (United States)

Morita, Yuka; Ebara, Fumio; Morita, Yoshimitsu; Horikawa, Etsuo

2017-08-01

[Purpose] Previous studies have indicated that animal-assisted therapy can promote recovery of psychological, social, and physiological function in mental disorders. This study was designed as a pilot evaluation of the use of near-infrared spectroscopy to objectively identify changes in brain activity that could mediate the effect of animal-assisted therapy. [Subjects and Methods] The participants were 20 healthy students (10 males and 10 females; age 19-21 years) of the Faculty of Agriculture, Saga University. Participants were shown a picture of a Tokara goat or shack (control) while prefrontal cortical oxygenated haemoglobin levels (representing neural activity) were measured by near-infrared spectroscopy. [Results] The prefrontal cortical near-infrared spectroscopy signal was significantly higher during viewing of the animal picture than during a rest condition or during viewing of the control picture. [Conclusion] Our results suggest that near-infrared spectroscopy can be used to objectively identify brain activity changes during human mentation regarding animals; furthermore, these preliminary results suggest the efficacy of animal-assisted therapy could be related to increased activation of the prefrontal cortex.

Metrological-grade tunable coherent source in the mid-infrared for molecular precision spectroscopy

Science.gov (United States)

Insero, G.; Clivati, C.; D'Ambrosio, D.; Cancio Pastor, P.; Verde, M.; Schunemann, P. G.; Zondy, J.-J.; Inguscio, M.; Calonico, D.; Levi, F.; De Natale, P.; Santambrogio, G.; Borri, S.

2018-02-01

We report on a metrological-grade mid-IR source with a 10-14 short-term instability for high-precision spectroscopy. Our source is based on the combination of a quantum cascade laser and a coherent radiation obtained by difference-frequency generation in an orientation-patterned gallium phosphide (OP-GaP) crystal. The pump and signal lasers are locked to an optical frequency comb referenced to the primary frequency standard via an optical fiber link. We demonstrate the robustness of the apparatus by measuring a vibrational transition around 6 μm on a metastable state of CO molecuels with 11 digits of precision.

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

CERN Document Server

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

2006-01-01

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

Two-dimensional vibrational spectroscopy of the amide I band of crystalline acetanilide: Fermi resonance, conformational substates, or vibrational self-trapping?

Science.gov (United States)

Edler, J.; Hamm, P.

2003-08-01

Two-dimensional infrared (2D-IR) spectroscopy is applied to investigate acetanilide, a molecular crystal consisting of quasi-one-dimensional hydrogen bonded peptide units. The amide-I band exhibits a double peak structure, which has been attributed to different mechanisms including vibrational self-trapping, a Fermi resonance, or the existence of two conformational substates. The 2D-IR spectrum of crystalline acetanilide is compared with that of two different molecular systems: (i) benzoylchloride, which exhibits a strong symmetric Fermi resonance and (ii) N-methylacetamide dissolved in methanol which occurs in two spectroscopically distinguishable conformations. Both 2D-IR spectra differ significantly from that of crystalline acetanilide, proving that these two alternative mechanisms cannot account for the anomalous spectroscopy of crystalline acetanilide. On the other hand, vibrational self-trapping of the amide-I band can naturally explain the 2D-IR response.

Fine structures of atomic excited states: precision atomic spectroscopy and electron-ion collision process

International Nuclear Information System (INIS)

Gao Xiang; Cheng Cheng; Li Jiaming

2011-01-01

Scientific research fields for future energies such as inertial confinement fusion researches and astrophysics studies especially with satellite observatories advance into stages of precision physics. The relevant atomic data are not only enormous but also of accuracy according to requirements, especially for both energy levels and the collision data. The fine structure of high excited states of atoms and ions can be measured by precision spectroscopy. Such precision measurements can provide not only knowledge about detailed dynamics of electron-ion interactions but also a bench mark examination of the accuracy of electron-ion collision data, especially incorporating theoretical computations. We illustrate that by using theoretical calculation methods which can treat the bound states and the adjacent continua on equal footing. The precision spectroscopic measurements of excited fine structures can be served as stringent tests of electron-ion collision data. (authors)

Confinement in a cryogenic Penning trap of highest charge state ions from EBIT

International Nuclear Information System (INIS)

Schneider, D.

1994-01-01

The retrapping of highly charged Xe 44+ and Th 68+,72+ ions extracted from an open-quotes Electron Beam Ion Trapclose quotes (EBIT) is demonstrated after injection of the ions into RETRAP, a cryogenic Penning trap (up to 6 Tesla magnetic field) currently with an open cylinder design. Ion extraction in a short pulse (5-20 μsec) from EBIT, essential for efficient retrapping, is employed. The ions are slowed down upon entering a deceleration tube mounted above the trap within the magnetic field. The potential is then rapidly (100 ns) decreased, enabling low energy ions to enter the trap. Capture efficiencies up to 25% are observed via detection of the delayed ion release pulse with a detector below the trap. Signal voltages induced in a tuned circuit due to single and multiple ions have been observed by tuning the ion resonant axial oscillation frequencies for different ions. Results from transporting and retrapping of the ions, as well as their detection, are described and the trapping efficiency is discussed, The motivation for these studies is to cool the trapped very highly charged ions to low temperatures (< 4 K) in order to perform ultrahigh resolution precision spectroscopy, collision studies at ultra low energies and to observe phase transitions in Coulomb clusters of highly charged ions

Spectroscopy of a Synthetic Trapped Ion Qubit

Science.gov (United States)

Hucul, David; Christensen, Justin E.; Hudson, Eric R.; Campbell, Wesley C.

2017-09-01

133Ba+ has been identified as an attractive ion for quantum information processing due to the unique combination of its spin-1 /2 nucleus and visible wavelength electronic transitions. Using a microgram source of radioactive material, we trap and laser cool the synthetic A =133 radioisotope of barium II in a radio-frequency ion trap. Using the same, single trapped atom, we measure the isotope shifts and hyperfine structure of the 62P1 /2↔62S1 /2 and 62P1 /2↔52D3 /2 electronic transitions that are needed for laser cooling, state preparation, and state detection of the clock-state hyperfine and optical qubits. We also report the 62P1 /2↔52D3 /2 electronic transition isotope shift for the rare A =130 and 132 barium nuclides, completing the spectroscopic characterization necessary for laser cooling all long-lived barium II isotopes.

A=225 implantation for $^{221}$Fr source for TRIUMF atom trap

CERN Multimedia

The FrPNC Collaboration is mounting an atom trap for parity violation experiments and precision spectroscopy on francium atoms at TRIUMF's ISAC facility. We would like to use ISOLDE's capability of simultaneously implanting A=225 (while another experiment runs online) to make a long-lived source feeding $^{221}$Fr for tests of the trap. $^{225}$Ra $\\beta$-decays to $^{225}$Ac, which then $\\alpha$-decays, producing 100 keV $^{221}$Fr t$_{1/2}$= 4.8 minute recoils. The implanted A=225 source would be shipped to TRIUMF, where it would be held for several minutes at a time a few mm from the same yttrium foil that normally receives the ISAC beam. SRIM calculations imply that 20% of the $^{221}$Fr will be implanted in a 1 cm diameter spot on the yttrium. Then the yttrium foil is moved to the trap and heated to release the Fr atoms, just as in normal ISAC online operation. A test implantation will be done at 10$^{7}$/sec production for 1 day, testing whether carbon cracking on the implantation foil in the mass separ...

Precision Muonium Spectroscopy

NARCIS (Netherlands)

Jungmann, Klaus P.

2016-01-01

The muonium atom is the purely leptonic bound state of a positive muon and an electron. It has a lifetime of 2.2 mu s. The absence of any known internal structure provides for precision experiments to test fundamental physics theories and to determine accurate values of fundamental constants. In

Deuterium trapping in tungsten

Science.gov (United States)

Poon, Michael

Tungsten is one of the primary material candidates being investigated for use in the first-wall of a magnetic confinement fusion reactor. An ion accelerator was used to simulate the type of ion interaction that may occur at a plasma-facing material. Thermal desorption spectroscopy (TDS) was the primary tool used to analyze the effects of the irradiation. Secondary ion mass spectroscopy (SIMS) was used to determine the distribution of trapped D in the tungsten specimen. The tritium migration analysis program (TMAP) was used to simulate thermal desorption profiles from the D depth distributions. Fitting of the simulated thermal desorption profiles with the measured TDS results provided values of the D trap energies. Deuterium trapping in single crystal tungsten was studied as a function of the incident ion fluence, ion flux, irradiation temperature, irradiation history, and surface impurity levels during irradiation. The results show that deuterium was trapped at vacancies and voids. Two deuterium atoms could be trapped at a tungsten vacancy, with trapping energies of 1.4 eV and 1.2 eV for the first and second D atoms, respectively. In a tungsten void, D is trapped as atoms adsorbed on the inner walls of the void with a trap energy of 2.1 eV, or as D2 molecules inside the void with a trap energy of 1.2 eV. Deuterium trapping in polycrystalline tungsten was also studied as a function of the incident fluence, irradiation temperature, and irradiation history. Deuterium trapping in polycrystalline tungsten also occurs primarily at vacancies and voids with the same trap energies as in single crystal tungsten; however, the presence of grain boundaries promotes the formation of large surface blisters with high fluence irradiations at 500 K. In general, D trapping is greater in polycrystalline tungsten than in single crystal tungsten. To simulate mixed materials comprising of carbon (C) and tungsten, tungsten specimens were pre-irradiated with carbon ions prior to D

Deuterium trapping in tungsten

International Nuclear Information System (INIS)

Poon, M.

2004-01-01

Tungsten is one of the primary material candidates being investigated for use in the first-wall of a magnetic confinement fusion reactor. An ion accelerator was used to simulate the type of ion interaction that may occur at a plasma-facing material. Thermal desorption spectroscopy (TDS) was the primary tool used to analyze the effects of the irradiation Secondary ion mass spectroscopy (SIMS) was used to determine the distribution of trapped D in the tungsten specimen. The tritium migration analysis program (TMAP) was used to simulate thermal desorption profiles from the D depth distributions. Fitting of the simulated thermal desorption profiles with the measured TDS results provided values of the D trap energies. . Deuterium trapping in single crystal tungsten was studied as a function of the incident ion fluence, ion flux, irradiation temperature, irradiation history, and surface impurity levels during irradiation The results show that deuterium was trapped at vacancies and voids. Two deuterium atoms could be trapped at a tungsten vacancy, with trapping energies of 1.4 eV and 1.2 eV for the first and second D atoms, respectively. In a tungsten void, D is trapped as atoms adsorbed on the inner walls of the void with a trap energy of 2.1 eV, or as D 2 molecules inside the void with a trap energy of 1.2 eV. . Deuterium trapping in polycrystalline tungsten was also studied as a function of the incident fluence, irradiation temperature, and irradiation history. Deuterium trapping in polycrystalline tungsten also occurs primarily at vacancies and voids with the same trap energies as in single crystal tungsten; however, the presence of grain boundaries promotes the formation of large surface blisters with high fluence irradiations at 500 K. In general, D trapping is greater in polycrystalline tungsten than in single crystal tungsten. To simulate mixed materials comprising of carbon (C) and tungsten, tungsten specimens were pre-irradiated with carbon ions prior to D

Deuterium trapping in tungsten

Energy Technology Data Exchange (ETDEWEB)

Poon, M

2004-07-01

Tungsten is one of the primary material candidates being investigated for use in the first-wall of a magnetic confinement fusion reactor. An ion accelerator was used to simulate the type of ion interaction that may occur at a plasma-facing material. Thermal desorption spectroscopy (TDS) was the primary tool used to analyze the effects of the irradiation Secondary ion mass spectroscopy (SIMS) was used to determine the distribution of trapped D in the tungsten specimen. The tritium migration analysis program (TMAP) was used to simulate thermal desorption profiles from the D depth distributions. Fitting of the simulated thermal desorption profiles with the measured TDS results provided values of the D trap energies. . Deuterium trapping in single crystal tungsten was studied as a function of the incident ion fluence, ion flux, irradiation temperature, irradiation history, and surface impurity levels during irradiation The results show that deuterium was trapped at vacancies and voids. Two deuterium atoms could be trapped at a tungsten vacancy, with trapping energies of 1.4 eV and 1.2 eV for the first and second D atoms, respectively. In a tungsten void, D is trapped as atoms adsorbed on the inner walls of the void with a trap energy of 2.1 eV, or as D{sub 2} molecules inside the void with a trap energy of 1.2 eV. . Deuterium trapping in polycrystalline tungsten was also studied as a function of the incident fluence, irradiation temperature, and irradiation history. Deuterium trapping in polycrystalline tungsten also occurs primarily at vacancies and voids with the same trap energies as in single crystal tungsten; however, the presence of grain boundaries promotes the formation of large surface blisters with high fluence irradiations at 500 K. In general, D trapping is greater in polycrystalline tungsten than in single crystal tungsten. To simulate mixed materials comprising of carbon (C) and tungsten, tungsten specimens were pre-irradiated with carbon ions prior to D

Precision laser spectroscopy of highly charged ions

International Nuclear Information System (INIS)

Kuehl, T.; Borneis, S.; Becker, S.; Dax, A.; Engel, T.; Grieser, R.; Huber, G.; Klaft, I.; Klepper, O.; Kohl, A.; Marx, D.; Meier, K.; Neumann, R.; Schmitt, F.; Seelig, P.; Voelker, L.

1996-01-01

Recently, intense beams of highly charged ions have become available at heavy ion cooler rings. The obstacle for producing these highly interesting candidates is the large binding energy of K-shell electrons in heavy systems in excess of 100 keV. One way to remove these electrons is to strip them off by passing the ion through material. In the cooler ring, the ions are cooled to a well defined velocity. At the SIS/ESR complex it is possible to produce, store, and cool highly charged ions up to bare uranium with intensities exceeding 10 8 atoms in the ring. This opens the door for precision laser spectroscopy of hydrogenlike-heavy ions, e.g. 209 Bi 82+ , and allows to examine the interaction of the single electron with the large fields of the heavy nucleus, exceeding any artificially produced electric and magnetic fields by orders of magnitude. In the electron cooler the interaction of electrons and highly charged ions otherwise only present in the hottest plasmas can be studied. (orig.)

Application of Computer-Assisted Learning Methods in the Teaching of Chemical Spectroscopy.

Science.gov (United States)

Ayscough, P. B.; And Others

1979-01-01

Discusses the application of computer-assisted learning methods to the interpretation of infrared, nuclear magnetic resonance, and mass spectra; and outlines extensions into the area of integrated spectroscopy. (Author/CMV)

Precision of coherence analysis to detect cerebral autoregulation by near-infrared spectroscopy in preterm infants

DEFF Research Database (Denmark)

Hahn, GH; Christensen, KB; Leung, TS

2010-01-01

Coherence between spontaneous fluctuations in arterial blood pressure (ABP) and the cerebral near-infrared spectroscopy signal can detect cerebral autoregulation. Because reliable measurement depends on signals with high signal-to-noise ratio, we hypothesized that coherence is more precisely...... determined when fluctuations in ABP are large rather than small. Therefore, we investigated whether adjusting for variability in ABP (variabilityABP) improves precision. We examined the impact of variabilityABP within the power spectrum in each measurement and between repeated measurements in preterm infants....... We also examined total monitoring time required to discriminate among infants with a simulation study. We studied 22 preterm infants (GAABP within the power spectrum did not improve the precision. However, adjusting...

Precision spectroscopy of the 2S-4P transition in atomic hydrogen

Science.gov (United States)

Maisenbacher, Lothar; Beyer, Axel; Matveev, Arthur; Grinin, Alexey; Pohl, Randolf; Khabarova, Ksenia; Kolachevsky, Nikolai; Hänsch, Theodor W.; Udem, Thomas

2017-04-01

Precision measurements of atomic hydrogen have long been successfully used to extract fundamental constants and to test bound-state QED. However, both these applications are limited by measurements of hydrogen lines other than the very precisely known 1S-2S transition. Moreover, the proton r.m.s.charge radius rp extracted from electronic hydrogen measurements currently disagrees by 4 σ with the much more precise value extracted from muonic hydrogen spectroscopy. We have measured the 2S-4P transition in atomic hydrogen using a cryogenic beam of hydrogen atoms optically excited to the initial 2S state. The first order Doppler shift of the one-photon 2S-4P transition is suppressed by actively stabilized counter-propagating laser beams and time-of-flight resolved detection. Quantum interference between excitation paths can lead to significant line distortions in our system. We use an experimentally verified, simple line shape model to take these distortions into account. With this, we can extract a new value for rp and the Rydberg constant R∞ with comparable accuracy as the combined previous H world data.

High-precision measurement of the electron spin g factor of trapped atomic nitrogen in the endohedral fullerene N@C60

Science.gov (United States)

Wittmann, J. J.; Can, T. V.; Eckardt, M.; Harneit, W.; Griffin, R. G.; Corzilius, B.

2018-05-01

The electronic g factor carries highly useful information about the electronic structure of a paramagnetic species, such as spin-orbit coupling and dia- or paramagnetic (de-)shielding due to local fields of surrounding electron pairs. However, in many cases, a near "spin-only" case is observed, in particular for light elements, necessitating accurate and precise measurement of the g factors. Such measurement is typically impeded by a "chicken and egg situation": internal or external reference standards are used for relative comparison of electron paramagnetic resonance (EPR) Larmor frequencies. However, the g factor of the standard itself usually is subject to a significant uncertainty which directly limits the precision and/or accuracy of the sought after sample g factor. Here, we apply an EPR reference-free approach for determining the g factor of atomic nitrogen trapped within the endohedral fullerene C60:N@C60 in its polycrystalline state by measuring the 1H NMR resonance frequency of dispersing toluene at room temperature. We found a value of g = 2.00204 (4) with a finally reached relative precision of ∼20 ppm. This accurate measurement allows us to directly compare the electronic properties of N@C60 to those found in atomic nitrogen in the gas phase or trapped in other solid matrices at liquid helium temperature. We conclude that spin-orbit coupling in N@C60 at room temperature is very similar in magnitude and of same sign as found in other inert solid matrices and that interactions between the quartet spin system and the C60 molecular orbitals are thus negligible.

Characterizing physical properties and heterogeneous chemistry of single particles in air using optical trapping-Raman spectroscopy

Science.gov (United States)

Gong, Z.; Wang, C.; Pan, Y. L.; Videen, G.

2017-12-01

Heterogeneous reactions of solid particles in a gaseous environment are of increasing interest; however, most of the heterogeneous chemistry studies of airborne solids were conducted on particle ensembles. A close examination on the heterogeneous chemistry between single particles and gaseous-environment species is the key to elucidate the fundamental mechanisms of hydroscopic growth, cloud nuclei condensation, secondary aerosol formation, etc., and reduce the uncertainty of models in radiative forcing, climate change, and atmospheric chemistry. We demonstrate an optical trapping-Raman spectroscopy (OT-RS) system to study the heterogeneous chemistry of the solid particles in air at single-particle level. Compared to other single-particle techniques, optical trapping offers a non-invasive, flexible, and stable method to isolate single solid particle from substrates. Benefited from two counter-propagating hollow beams, the optical trapping configuration is adaptive to trap a variety of particles with different materials from inorganic substitution (carbon nanotubes, silica, etc.) to organic, dye-doped polymers and bioaerosols (spores, pollen, etc.), with different optical properties from transparent to strongly absorbing, with different sizes from sub-micrometers to tens of microns, or with distinct morphologies from loosely packed nanotubes to microspheres and irregular pollen grains. The particles in the optical trap may stay unchanged, surface degraded, or optically fragmented according to different laser intensity, and their physical and chemical properties are characterized by the Raman spectra and imaging system simultaneously. The Raman spectra is able to distinguish the chemical compositions of different particles, while the synchronized imaging system can resolve their physical properties (sizes, shapes, morphologies, etc.). The temporal behavior of the trapped particles also can be monitored by the OT-RS system at an indefinite time with a resolution from

Study on ECH-assisted start-up using trapped particle configuration in KSTAR and application to ITER

Science.gov (United States)

Lee, Jeongwon; Kim, Jayhyun; An, YoungHwa; Yoo, Min-Gu; Hwang, Y. S.; Na, Yong-Su

2017-12-01

ECH-assisted start-up using trapped particle configuration (TPC) is firstly studied in a superconducting, conventional tokamak, KSTAR. First, improved and efficient start-up using TPC than conventional field null configuration (FNC) is achieved by enhanced pre-ionization plasma quality. TPC shows the broader operation window in terms of the poloidal field quality and the deuterium prefill pressure than that of FNC. Surprisingly the particle trapping enhances the plasma start-up performance even with much lower particle trapping ratio than that of spherical torus. Reliability of TPC with low trapping ratio is investigated by 0D plasma evolution code, TECHP0D. Second, the characteristics of TPC start-up are explored with experiments and modellings. Two kind of start-up failure conditions are identified by the magnetic pitch and prefill pressure scan experiments: (i) low ionization rate; and (ii) low density condition. These experimental observation has consistency with TECHP0D modeling result. Finally, reliable ITER-relevant low toroidal electric field start-up using TPC is achieved with drastically improved success rate of start-up in KSTAR. In this experiments, validity of the ITER-like toroidally inclined ECH/ECCD injection is also expected. Time dependent ITER start-up scenario using TPC is proposed and the superiority of it than FNC is discussed.

PRECISE:PRivacy-prEserving Cloud-assisted quality Improvement Service in hEalthcare.

Science.gov (United States)

Chen, Feng; Wang, Shuang; Mohammed, Noman; Cheng, Samuel; Jiang, Xiaoqian

2014-10-01

Quality improvement (QI) requires systematic and continuous efforts to enhance healthcare services. A healthcare provider might wish to compare local statistics with those from other institutions in order to identify problems and develop intervention to improve the quality of care. However, the sharing of institution information may be deterred by institutional privacy as publicizing such statistics could lead to embarrassment and even financial damage. In this article, we propose a PRivacy-prEserving Cloud-assisted quality Improvement Service in hEalthcare (PRECISE), which aims at enabling cross-institution comparison of healthcare statistics while protecting privacy. The proposed framework relies on a set of state-of-the-art cryptographic protocols including homomorphic encryption and Yao's garbled circuit schemes. By securely pooling data from different institutions, PRECISE can rank the encrypted statistics to facilitate QI among participating institutes. We conducted experiments using MIMIC II database and demonstrated the feasibility of the proposed PRECISE framework.

Optical trapping of carbon nanotubes and graphene

Directory of Open Access Journals (Sweden)

S. Vasi

2011-09-01

Full Text Available We study optical trapping of nanotubes and graphene. We extract the distribution of both centre-of-mass and angular fluctuations from three-dimensional tracking of these optically trapped carbon nanostructures. The optical force and torque constants are measured from auto and cross-correlation of the tracking signals. We demonstrate that nanotubes enable nanometer spatial, and femto-Newton force resolution in photonic force microscopy by accurately measuring the radiation pressure in a double frequency optical tweezers. Finally, we integrate optical trapping with Raman and photoluminescence spectroscopy demonstrating the use of a Raman and photoluminescence tweezers by investigating the spectroscopy of nanotubes and graphene flakes in solution. Experimental results are compared with calculations based on electromagnetic scattering theory.

New experimental initiatives using very highly charged ions from an 'electron beam ion trap'

International Nuclear Information System (INIS)

Schneider, D.

1996-01-01

A short review of the experimental program in highly-charged heavy ion physics conducted at the Lawrence Livermore National Laboratory Electron Beam Ion Trap (EBIT) facility is presented. The heavy-ion research, involving ions up to fully stripped U 92+ , includes precision x-ray spectroscopy and lifetime studies, electron impact ionization and excitation cross section measurements. The investigations of ion-surface interactions following the impact of high-Z highly charged ions on surfaces are aimed to study the neutralization dynamics effecting the ion and the response of the surface as well. (author)

Precise mass measurements of astrophysical interest made with the Canadian Penning trap mass spectrometer

International Nuclear Information System (INIS)

Clark, J.A.; Barber, R.C.; Blank, B.; Boudreau, C.; Buchinger, F.; Crawford, J.E.; Gulick, S.; Hardy, J.C.; Heinz, A.; Lee, J.K.P.; Levand, A.F.; Moore, R.B.; Savard, G.; Seweryniak, D.; Sharma, K.S.; Sprouse, G.D.; Trimble, W.; Vaz, J.; Wang, J.C.; Zhou, Z.

2004-01-01

The processes responsible for the creation of elements more massive than iron are not well understood. Possible production mechanisms involve the rapid capture of protons (rp-process) or the rapid capture of neutrons (r-process), which are thought to occur in explosive astrophysical events such as novae, x-ray bursts, and supernovae. Mass measurements of the nuclides involved with uncertainties on the order of 100 keV or better are critical to determine the process 'paths', the energy output of the events, and the resulting nuclide abundances. Particularly important are the masses of 'waiting-point' nuclides along the rp-process path where the process stalls until the subsequent β decay of the nuclides. This paper will discuss the precise mass measurements made of isotopes along the rp-process and r-process paths using the Canadian Penning Trap mass spectrometer, including the mass of the critical waiting-point nuclide 68 Se

Trap-assisted tunneling in aluminum-doped ZnO/indium oxynitride nanodot interlayer Ohmic contacts on p-GaN

Energy Technology Data Exchange (ETDEWEB)

Ke, Wen-Cheng, E-mail: wcke@mail.ntust.edu.tw; Yang, Cheng-Yi [Department of Materials Science and Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan (China); Lee, Fang-Wei; Chen, Wei-Kuo [Department of Electrophysics, National Chiao-Tung University, Hsin-Chu 300, Taiwan (China); Huang, Hao-Ping [Department of Mechanical Engineering, Yuan Ze University, Chung-Li 320, Taiwan (China)

2015-10-21

This study developed an Ohmic contact formation method for a ZnO:Al (AZO) transparent conductive layer on p-GaN films involving the introduction of an indium oxynitride (InON) nanodot interlayer. An antisurfactant pretreatment was used to grow InON nanodots on p-GaN films in a RF magnetron sputtering system. A low specific contact resistance of 1.12 × 10{sup −4} Ω cm{sup 2} was achieved for a sample annealed at 500 °C for 30 s in nitrogen ambient and embedded with an InON nanodot interlayer with a nanodot density of 6.5 × 10{sup 8} cm{sup −2}. By contrast, a sample annealed in oxygen ambient exhibited non-Ohmic behavior. X-ray photoemission spectroscopy results showed that the oxygen vacancy (V{sub o}) in the InON nanodots played a crucial role in carrier transport. The fitting I–V characteristic curves indicated that the hopping mechanism with an activation energy of 31.6 meV and trap site spacing of 1.1 nm dominated the carrier transport in the AZO/InON nanodot/p-GaN sample. Because of the high density of donor-like oxygen vacancy defects at the InON nanodot/p-GaN interface, positive charges from the underlying p-GaN films were absorbed at the interface. This led to positive charge accumulation, creating a narrow depletion layer; therefore, carriers from the AZO layer passed through InON nanodots by hopping transport, and subsequently tunneling through the interface to enter the p-GaN films. Thus, AZO Ohmic contact can be formed on p-GaN films by embedding an InON nanodot interlayer to facilitate trap-assisted tunneling.

Search For Trapped Antihydrogen

CERN Document Server

Andresen, Gorm B.; Baquero-Ruiz, Marcelo; Bertsche, William; Bowe, Paul D.; Bray, Crystal C.; Butler, Eoin; Cesar, Claudio L.; Chapman, Steven; Charlton, Michael; Fajans, Joel; Friesen, Tim; Fujiwara, Makoto C.; Gill, David R.; Hangst, Jeffrey S.; Hardy, Walter N.; Hayano, Ryugo S.; Hayden, Michael E.; Humphries, Andrew J.; Hydomako, Richard; Jonsell, Svante; Jorgensen, Lars V.; Kurchaninov, Lenoid; Lambo, Ricardo; Madsen, Niels; Menary, Scott; Nolan, Paul; Olchanski, Konstantin; Olin, Art; Povilus, Alexander; Pusa, Petteri; Robicheaux, Francis; Sarid, Eli; Nasr, Sarah Seif El; Silveira, Daniel M.; So, Chukman; Storey, James W.; Thompson, Robert I.; van der Werf, Dirk P.; Wilding, Dean; Wurtele, Jonathan S.; Yamazaki, Yasunori

2011-01-01

We present the results of an experiment to search for trapped antihydrogen atoms with the ALPHA antihydrogen trap at the CERN Antiproton Decelerator. Sensitive diagnostics of the temperatures, sizes, and densities of the trapped antiproton and positron plasmas have been developed, which in turn permitted development of techniques to precisely and reproducibly control the initial experimental parameters. The use of a position-sensitive annihilation vertex detector, together with the capability of controllably quenching the superconducting magnetic minimum trap, enabled us to carry out a high-sensitivity and low-background search for trapped synthesised antihydrogen atoms. We aim to identify the annihilations of antihydrogen atoms held for at least 130 ms in the trap before being released over ~30 ms. After a three-week experimental run in 2009 involving mixing of 10^7 antiprotons with 1.3 10^9 positrons to produce 6 10^5 antihydrogen atoms, we have identified six antiproton annihilation events that are consist...

Research status in ultra-precision machining of silicon carbide parts by oxidation-assisted polishing

Directory of Open Access Journals (Sweden)

Xinmin SHEN

2016-10-01

Full Text Available Oxidation-assisted polishing is an important machining method for obtaining SiC parts with high precision. Through plasma oxidation, thermal oxidation, and anodic oxidation, soft oxide can be obtained on the RS-SiC substrate. With the assistance of abrasive polishing to remove the oxide rapidly, the material removal rate can be increased and the surface quality can be improved. The research results indicate that the surface roughness root-mean-square (RMS and roughness-average (Ra can reach 0.626 nm and 0.480 nm by plasma oxidation-assisted polishing; in thermal oxidation-assisted polishing, the RMS and Ra can be 0.920 nm and 0.726 nm; in anodic oxidation, the calculated oxidation rate is 5.3 nm/s based on Deal-Grove model, and the RMS and Ra are 4.428 nm and 3.453 nm respectively in anodic oxidation-assisted polishing. The oxidation-assisted polishing can be propitious to improve the process level in machining RS-SiC, which would promote the application of SiC parts in optics and ceramics fields.

Ultracold molecules for the masses: Evaporative cooling and magneto-optical trapping

Science.gov (United States)

Stuhl, B. K.

While cold molecule experiments are rapidly moving towards their promised benefits of precision spectroscopy, controllable chemistry, and novel condensed phases, heretofore the field has been greatly limited by a lack of methods to cool and compress chemically diverse species to temperatures below ten millikelvin. While in atomic physics these needs are fulfilled by laser cooling, magneto-optical trapping, and evaporative cooling, until now none of these techniques have been applicable to molecules. In this thesis, two major breakthroughs are reported. The first is the observation of evaporative cooling in magnetically trapped hydroxyl (OH) radicals, which potentially opens a path all the way to Bose-Einstein condensation of dipolar radicals, as well as allowing cold- and ultracold-chemistry studies of fundamental reaction mechanisms. Through the combination of an extremely high gradient magnetic quadrupole trap and the use of the OH Λ-doublet transition to enable highly selective forced evaporation, cooling by an order of magnitude in temperature was achieved and yielded a final temperature no higher than 5mK. The second breakthrough is the successful application of laser cooling and magneto-optical trapping to molecules. Motivated by a proposal in this thesis, laser cooling of molecules is now known to be technically feasible in a select but substantial pool of diatomic molecules. The demonstration of not only Doppler cooling but also two-dimensional magneto-optical trapping in yttrium (II) oxide, YO, is expected to enable rapid growth in the availability of ultracold molecules—just as the invention of the atomic magneto-optical trap stimulated atomic physics twenty-five years ago.

Calibrated high-precision 17O-excess measurements using cavity ring-down spectroscopy with laser-current-tuned cavity resonance

Directory of Open Access Journals (Sweden)

E. J. Steig

2014-08-01

Full Text Available High-precision analysis of the 17O / 16O isotope ratio in water and water vapor is of interest in hydrological, paleoclimate, and atmospheric science applications. Of specific interest is the parameter 17O excess (Δ17O, a measure of the deviation from a~linear relationship between 17O / 16O and 18O / 16O ratios. Conventional analyses of Δ17O of water are obtained by fluorination of H2O to O2 that is analyzed by dual-inlet isotope ratio mass spectrometry (IRMS. We describe a new laser spectroscopy instrument for high-precision Δ17O measurements. The new instrument uses cavity ring-down spectroscopy (CRDS with laser-current-tuned cavity resonance to achieve reduced measurement drift compared with previous-generation instruments. Liquid water and water-vapor samples can be analyzed with a better than 8 per meg precision for Δ17O using integration times of less than 30 min. Calibration with respect to accepted water standards demonstrates that both the precision and the accuracy of Δ17O are competitive with conventional IRMS methods. The new instrument also achieves simultaneous analysis of δ18O, Δ17O and δD with precision of < 0.03‰, < 0.02 and < 0.2‰, respectively, based on repeated calibrated measurements.

Atomic and nuclear physics with stored particles in ion traps

CERN Document Server

Kluge, H J; Herfurth, F; Quint, W

2002-01-01

Trapping and cooling techniques play an increasingly important role in many areas of science. This review concentrates on recent applications of ion traps installed at accelerator facilities to atomic and nuclear physics such as mass spectrometry of radioactive isotopes, weak interaction studies, symmetry tests, determination of fundamental constants, laser spectroscopy, and spectroscopy of highly-charged ions. In addition, ion traps are proven to be extremely efficient devices for (radioactive) ion beam manipulation as, for example, retardation, accumulation, cooling, beam cleaning, charge-breeding, and bunching.

Non-destructive state detection for quantum logic spectroscopy of molecular ions.

Science.gov (United States)

Wolf, Fabian; Wan, Yong; Heip, Jan C; Gebert, Florian; Shi, Chunyan; Schmidt, Piet O

2016-02-25

Precision laser spectroscopy of cold and trapped molecular ions is a powerful tool in fundamental physics--used, for example, in determining fundamental constants, testing for their possible variation in the laboratory, and searching for a possible electric dipole moment of the electron. However, the absence of cycling transitions in molecules poses a challenge for direct laser cooling of the ions, and for controlling and detecting their quantum states. Previously used state-detection techniques based on photodissociation or chemical reactions are destructive and therefore inefficient, restricting the achievable resolution in laser spectroscopy. Here, we experimentally demonstrate non-destructive detection of the quantum state of a single trapped molecular ion through its strong Coulomb coupling to a well controlled, co-trapped atomic ion. An algorithm based on a state-dependent optical dipole force changes the internal state of the atom according to the internal state of the molecule. We show that individual quantum states in the molecular ion can be distinguished by the strength of their coupling to the optical dipole force. We also observe quantum jumps (induced by black-body radiation) between rotational states of a single molecular ion. Using the detuning dependence of the state-detection signal, we implement a variant of quantum logic spectroscopy of a molecular resonance. Our state-detection technique is relevant to a wide range of molecular ions, and could be applied to state-controlled quantum chemistry and to spectroscopic investigations of molecules that serve as probes for interstellar clouds.

Laser trapping of 21Na atoms

International Nuclear Information System (INIS)

Lu, Zheng-Tian.

1994-09-01

This thesis describes an experiment in which about four thousand radioactive 21 Na (t l/2 = 22 sec) atoms were trapped in a magneto-optical trap with laser beams. Trapped 21 Na atoms can be used as a beta source in a precision measurement of the beta-asymmetry parameter of the decay of 21 Na → 21 Ne + Β + + v e , which is a promising way to search for an anomalous right-handed current coupling in charged weak interactions. Although the number o trapped atoms that we have achieved is still about two orders of magnitude lower than what is needed to conduct a measurement of the beta-asymmetry parameter at 1% of precision level, the result of this experiment proved the feasibility of trapping short-lived radioactive atoms. In this experiment, 21 Na atoms were produced by bombarding 24 Mg with protons of 25 MeV at the 88 in. Cyclotron of Lawrence Berkeley Laboratory. A few recently developed techniques of laser manipulation of neutral atoms were applied in this experiment. The 21 Na atoms emerging from a heated oven were first transversely cooled. As a result, the on-axis atomic beam intensity was increased by a factor of 16. The atoms in the beam were then slowed down from thermal speed by applying Zeeman-tuned slowing technique, and subsequently loaded into a magneto-optical trap at the end of the slowing path. The last two chapters of this thesis present two studies on the magneto-optical trap of sodium atoms. In particular, the mechanisms of magneto-optical traps at various laser frequencies and the collisional loss mechanisms of these traps were examined

Precision Isotope Shift Measurements in Calcium Ions Using Quantum Logic Detection Schemes.

Science.gov (United States)

Gebert, Florian; Wan, Yong; Wolf, Fabian; Angstmann, Christopher N; Berengut, Julian C; Schmidt, Piet O

2015-07-31

We demonstrate an efficient high-precision optical spectroscopy technique for single trapped ions with nonclosed transitions. In a double-shelving technique, the absorption of a single photon is first amplified to several phonons of a normal motional mode shared with a cotrapped cooling ion of a different species, before being further amplified to thousands of fluorescence photons emitted by the cooling ion using the standard electron shelving technique. We employ this extension of the photon recoil spectroscopy technique to perform the first high precision absolute frequency measurement of the 2D(3/2)→2P(1/2) transition in calcium, resulting in a transition frequency of f=346 000 234 867(96)  kHz. Furthermore, we determine the isotope shift of this transition and the 2S(1/2)→2P(1/2) transition for 42Ca+, 44Ca+, and 48Ca+ ions relative to 40Ca+ with an accuracy below 100 kHz. Improved field and mass shift constants of these transitions as well as changes in mean square nuclear charge radii are extracted from this high resolution data.

EPR reversible signature of self-trapped holes in fictive temperature-treated silica glass

Science.gov (United States)

Lancry, Matthieu; Ollier, Nadège; Babu, B. H.; Herrero, Christian; Poumellec, Bertrand

2018-03-01

Post-mortem electron paramagnetic resonance spectroscopy experiments have been carried out between room temperature and 20 K to examine the radiation-induced defects in fictive temperature (Tf) treated Heraeus F300 silica (0.1 ppm OH, 1500 ppm Cl2). In particular, we focus our attention on Self-Trapped Hole (STH) centers detected in 1000 °C, 1100 °C, and 1200 °C Tf treated samples irradiated at room temperature by gamma rays at 6 kGy. By repeating annealing cycles between 77 and 300 K on the same samples, we observed that the EPR signal attributed to STH decreases as the temperature increases but in a reversible manner. We evidenced a deviation from the Curie law for T > 70 K and suggested an interpretation based on the decrease in the "strain-assisted TH" population by reversible excitation of the trapped hole to a delocalized state with an activation energy of 7.8 meV. This also means that the precursors of hole trapping sites (a local strain atomic configuration) remain stable until 300 K at least.

Development of an experiment for ultrahigh-precision g-factor measurements in a Penning-trap setup

Energy Technology Data Exchange (ETDEWEB)

Alonso Otamendi, J.

2007-07-13

This thesis is concerned with the design and construction of an experimental setup aiming to perform ultrahigh-precision g-factor measurements on a bound electron in highly-charged ions. The g-factor of a particle is a dimensionless constant which determines the strength of its interaction with a magnetic field. In the case of an electron bound to a highly-charged ion, it serves as one of the most stringent tests of bound-state quantum electrodynamics (BS-QED). The measurement is based on a triple-Penning-trap system and the continuous Stern-Gerlach effect. The first part of the thesis is devoted to the current knowledge on magnetic moments and motivates the techniques and experimental setup used during the work described. As a major challenge to overcome, the charge breeding of the ions is dealt with in detail, along with the solution found, based on a field-emission-point array. The tools included allow for the measurement of ionization cross-sections by electron impact. The last part of the thesis is dedicated to the design and operation of the triple-Penning-trap setup and the detection schemes implemented. At present, all the experimental setup for the production of highly-charged ions and the corresponding g-factor measurement is completely finalized, including the control system needed for the first measurement stages, so the ion-creation and charge-breeding processes will be the next steps to be taken. (orig.)

Development of an experiment for ultrahigh-precision g-factor measurements in a Penning-trap setup

International Nuclear Information System (INIS)

Alonso Otamendi, J.

2007-01-01

This thesis is concerned with the design and construction of an experimental setup aiming to perform ultrahigh-precision g-factor measurements on a bound electron in highly-charged ions. The g-factor of a particle is a dimensionless constant which determines the strength of its interaction with a magnetic field. In the case of an electron bound to a highly-charged ion, it serves as one of the most stringent tests of bound-state quantum electrodynamics (BS-QED). The measurement is based on a triple-Penning-trap system and the continuous Stern-Gerlach effect. The first part of the thesis is devoted to the current knowledge on magnetic moments and motivates the techniques and experimental setup used during the work described. As a major challenge to overcome, the charge breeding of the ions is dealt with in detail, along with the solution found, based on a field-emission-point array. The tools included allow for the measurement of ionization cross-sections by electron impact. The last part of the thesis is dedicated to the design and operation of the triple-Penning-trap setup and the detection schemes implemented. At present, all the experimental setup for the production of highly-charged ions and the corresponding g-factor measurement is completely finalized, including the control system needed for the first measurement stages, so the ion-creation and charge-breeding processes will be the next steps to be taken. (orig.)

EBIT (Electron Beam Ion Trap), N-Division Experimental Physics. Annual report, 1994

International Nuclear Information System (INIS)

Schneider, D.

1995-10-01

The experimental groups in the Electron Beam Ion Trap (EBIT) program continue to perform front-line research with trapped and extracted highly charged ions (HCI) in the areas of ion/surface interactions, atomic spectroscopy, electron-ion interaction and structure measurements, highly charged ion confinement, and EBIT development studies. The ion surface/interaction studies which were initiated five years ago have reached a stage where they an carry out routine investigations, as well as produce breakthrough results towards the development of novel nanotechnology. At EBIT and SuperEBIT studies of the x-ray emission from trapped ions continue to produce significant atomic structure data with high precision for few electron systems of high-Z ions. Furthermore, diagnostics development for magnetic and laser fusion, supporting research for the x-ray laser and weapons programs, and laboratory astrophysics experiments in support of NASA's astrophysics program are a continuing effort. The two-electron contributions to the binding energy of helium like ions were measured for the first time. The results are significant because their precision is an order of magnitude better than those of competing measurements at accelerators, and the novel technique isolates the energy corrections that are the most interesting. The RETRAP project which was initiated three years ago has reached a stage where trapping, confining and electronic cooling of HCI ions up to Th 80+ can be performed routinely. Measurements of the rates and cross sections for electron transfer from H 2 performed to determine the lifetime of HCI up to Xe q+ and Th q+ (35 ≤ q ≤ 80) have been studied at mean energies estimated to be ∼ 5 q eV. This combination of heavy ions with very high charges and very low energies is rare in nature, but may be encountered in planned fusion energy demonstration devices, in highly charged ion sources, or in certain astrophysical events

Quantitative evaluation of spatial scale of carrier trapping at grain boundary by GHz-microwave dielectric loss spectroscopy

Science.gov (United States)

Choi, W.; Tsutsui, Y.; Miyakai, T.; Sakurai, T.; Seki, S.

2017-11-01

Charge carrier mobility is an important primary parameter for the electronic conductive materials, and the intrinsic limit of the mobility has been hardly access by conventional direct-current evaluation methods. In the present study, intra-grain hole mobility of pentacene thin films was estimated quantitatively using microwave-based dielectric loss spectroscopy (time-resolved microwave conductivity measurement) in alternating current mode of charge carrier local motion. Metal-insulator-semiconductor devices were prepared with different insulating polymers or substrate temperature upon vacuum deposition of the pentacene layer, which afforded totally four different grain-size conditions of pentacene layers. Under the condition where the local motion was determined by interfacial traps at the pentacene grain boundaries (grain-grain interfaces), the observed hole mobilities were plotted against the grain sizes, giving an excellent correlation fit successfully by a parabolic function representative of the boarder length. Consequently, the intra-grain mobility and trap-release time of holes were estimated as 15 cm2 V-1 s-1 and 9.4 ps.

Optical analysis of trapped Gas—Gas in Scattering Media Absorption Spectroscopy

Science.gov (United States)

Svanberg, S.

2010-01-01

An overview of the new field of Gas in Scattering Media Absorption Spectroscopy (GASMAS) is presented. The technique investigates sharp gas spectral signatures, typically 10000 times sharper than those of the host material, in which the gas is trapped in pores or cavities. The presence of pores causes strong multiple scattering. GASMAS combines narrow-band diode-laser spectroscopy, developed for atmospheric gas monitoring, with diffuse media optical propagation, well-known from biomedical optics. Several applications in materials science, food packaging, pharmaceutics and medicine have been demonstrated. So far molecular oxygen and water vapour have been studied around 760 and 935 nm, respectively. Liquid water, an important constituent in many natural materials, such as tissue, has a low absorption at such wavelengths, and this is also true for haemoglobin, making propagation possible in many natural materials. Polystyrene foam, wood, fruits, food-stuffs, pharmaceutical tablets, and human sinus cavities (frontal, maxillary and mastoideal) have been studied, demonstrating new possibilities for characterization and diagnostics. Transport of gas in porous media (diffusion) can be studied by first subjecting the material to, e.g., pure nitrogen, and then observing the rate at which normal, oxygen-containing air, reinvades the material. The conductance of the passages connecting a sinus with the nasal cavity can be objectively assessed by observing the oxygen gas dynamics when flushing the nose with nitrogen. Drying of materials, when liquid water is replaced by air and water vapour, is another example of dynamic processes which can be studied. The technique has also been extended to remote-sensing applications (LIDAR-GASMAS or Multiple-Scattering LIDAR).

Effect of oxide charge trapping on x-ray photoelectron spectroscopy of HfO2/SiO2/Si structures

International Nuclear Information System (INIS)

Abe, Yasuhiro; Miyata, Noriyuki; Suzuki, Haruhiko; Kitamura, Koji; Igarashi, Satoru; Nohira, Hiroshi; Ikenaga, Eiji

2009-01-01

We examined the effects of interfacial SiO 2 layers and a surface metal layer on the photoelectron spectra of HfO 2 /SiO 2 /Si structures by hard X-ray photoemission spectroscopy with synchrotron radiation as well as conventional X-ray photoelectron spectroscopy (XPS). The Hf 4f and Hf 3d photoelectron peaks broadened and shifted toward a higher binding energy with increasing thickness of the interfacial SiO 2 layer, even though photoelectrons may have been emitted from the HfO 2 layer with the same chemical composition. Thinning the interfacial Si oxide layer to approximately one monolayer and depositing a metal layer on the HfO 2 surface suppressed these phenomena. The O 1s photoelectron spectra revealed marked differences between the metal- and nonmetal-deposited HfO 2 /SiO 2 /Si structures; HfO 2 and SiO 2 components in the O 1s photoelectron spectra for the metal-deposited structures were observed at reasonably separated binding energies, but those for the nonmetal-deposited structures were not separated clearly. From this behavior concerning the effects of interfacial SiO 2 and surface metal layers, we concluded that the Hf 4f, Hf 3d, and O 1s spectra measured from the HfO 2 /SiO 2 /Si structures did not reflect actual chemical bonding states. We consider that potential variations in the HfO 2 film owing to charge trapping strongly affect the measured photoelectron spectra. On the basis of angle-resolved XPS measurements, we propose that positive charges are trapped at the HfO 2 surface and negative charges are trapped inside the HfO 2 layer. (author)

Practical aspects of trapped ion mass spectrometry, 5 applications of ion trapping devices

CERN Document Server

March, Raymond E

2009-01-01

Examines ion/neutral and ion/ion reactions, ion spectroscopy, and the structural characterization of proteins and peptides using quadropole ion trap mass spectrometry, Fourier transform - ion cyclotron resonance (FT-ICR) mass spectrometry, and traveling wave ion mobility mass spectrometry.

Single Ion Trapping for the Enriched Xenon Observatory

Energy Technology Data Exchange (ETDEWEB)

Waldman, Samuel J.; /Stanford U., Phys. Dept. /SLAC

2006-03-28

In the last decade, a variety of neutrino oscillation experiments have established that there is a mass difference between neutrino flavors, without determining the absolute neutrino mass scale. The Enriched Xenon Observatory for neutrinoless double beta decay (EXO) will search for the rare decays of xenon to determine the absolute value of the neutrino mass. The experiment uses a novel technique to minimize backgrounds, identifying the decay daughter product in real time using single ion spectroscopy. Here, we describe single ion trapping and spectroscopy compatible with the EXO detector. We extend the technique of single ion trapping in ultrahigh vacuum to trapping in xenon gas. With this technique, EXO will achieve a neutrino mass sensitivity of {approx_equal} .010 eV.

Trapped antihydrogen

CERN Document Server

Butler, E; Ashkezari, M D; Baquero-Ruiz, M; Bertsche, W; Bowe, P D; Cesar, C L; Chapman, S; Charlton, M; Deller, A; Eriksson, S; Fajans, J; Friesen, T; Fujiwara, M C; Gill, D R; Gutierrez, A; Hangst, J S; Hardy, W N; Hayden, M E; Humphries, A J; Hydomako, R; Jenkins, M J; Jonsell, S; Jørgensen, L V; Kemp, S L; Kurchaninov, L; Madsen, N; Menary, S; Nolan, P; Olchanski, K; Olin, A; Povilus, A; Pusa, P; Rasmussen, C Ø; Robicheaux, F; Sarid, E; Seif el Nasr, S; Silveira, D M; So, C; Storey, J W; Thompson, R I; van der Werf, D P; Wurtele, J S; Yamazaki,Y

2012-01-01

Precision spectroscopic comparison of hydrogen and antihydrogen holds the promise of a sensitive test of the Charge-Parity-Time theorem and matter-antimatter equivalence. The clearest path towards realising this goal is to hold a sample of antihydrogen in an atomic trap for interrogation by electromagnetic radiation. Achieving this poses a huge experimental challenge, as state-of-the-art magnetic-minimum atom traps have well depths of only ∼1 T (∼0.5 K for ground state antihydrogen atoms). The atoms annihilate on contact with matter and must be ‘born’ inside the magnetic trap with low kinetic energies. At the ALPHA experiment, antihydrogen atoms are produced from antiprotons and positrons stored in the form of non-neutral plasmas, where the typical electrostatic potential energy per particle is on the order of electronvolts, more than 104 times the maximum trappable kinetic energy. In November 2010, ALPHA published the observation of 38 antiproton annihilations due to antihydrogen atoms that had been ...

Theoretical and instrumental aspects of preparation of radioactive sources for precise nuclear spectroscopy

International Nuclear Information System (INIS)

Babenkov, M.I.; Kadyrzhanov, K.K.; Zhdanov, V.S.

2005-01-01

Full text: Precise investigations of spectra from nuclear radiations are quite sensitive to quality of radiation sources used. In an ideal case a source should introduce no noticeable distortion into registered spectrum. In spectroscopy of low-energy gamma-quanta, electrons and alpha particles sample preparation quite frequently turns to be challenging independent scientific investigation. Source preparation is conventionally performed at two stages - extraction of activity from a target and its uniform distribution over a substrate. A general requirement to such radioactive layer is maximal total and specific activity. Unfortunately, there is no universal source preparation method currently available for precise spectroscopy. In a number of cases excellent results are provided by fractional sublimation method based on ability of some elements to evaporate from target material at heating. The method demonstrates a several advantages. The paper introduces a complex of experimental equipment for preparation of high-quality radioactive sources. This complex is arranged in a well-protected heavy box equipped with master-slave manipulators. Biological protection of the box makes it possible to handle activities up to 10 11 Bq. Main part of the complex is a special vacuum post that assures works with active samples in the vacuum up to 10 -7 mm Hg - the operations include fractional sublimation, thermal evaporation, thermal diffusion, evaporation by electron beam, etc. All units of the vacuum post arranged in the box are designed to work with master-slave manipulators. The post is mainly used for preparation of a high-quality beta sources and extraction of microamounts of radionuclides from reactor and cyclotron targets by the method of fractional sublimation. Another important unit of the complex is an equipment for selective chemisorption in vacuum. Complex comprises all required auxiliary equipment The entire complex operated at high rate of reliability. The paper pays

Doppler-shift assisted fast ion spectroscopy: a case study for X-ray emission from 277 MeV/u Pb[81+] ions

International Nuclear Information System (INIS)

Mokler, P.H.; Stoehlker, T.; Kozhuharov, C.; Moshammer, R.; Rymuza, P.; Stachura, Z.; Warczak, A.

1994-09-01

Utilizing the different information from spatially separated segments of high-granular photon detectors the measured (LAB) energy of photons emitted by fast moving ions can be corrected individually for the Doppler effect according to the particular observation angles of each detector segment. By a redundant fitting procedure the center of mass photon energy can be determined with high precision. This new Doppler-shift assisted spectroscopy is explained for the case study of 277.4 MeV/u Pb 82+ ions colliding with a N 2 -gas target at the heavy ion storage ring ESR. Spectroscopic information for hydrogenic Pb 81+ ions is given for the ground-state transitions, for the Balmer transitions, as well as for the total K-binding energy. (orig.)

Diffractive optical devices produced by light-assisted trapping of nanoparticles.

Science.gov (United States)

Muñoz-Martínez, J F; Jubera, M; Matarrubia, J; García-Cabañes, A; Agulló-López, F; Carrascosa, M

2016-01-15

One- and two-dimensional diffractive optical devices have been fabricated by light-assisted trapping and patterning of nanoparticles. The method is based on the dielectrophoretic forces appearing in the vicinity of a photovoltaic crystal, such as Fe:LiNbO3, during or after illumination. By illumination with the appropriate light distribution, the nanoparticles are organized along patterns designed at will. One- and two-dimensional diffractive components have been achieved on X- and Z-cut Fe:LiNbO3 crystals, with their polar axes parallel and perpendicular to the crystal surface, respectively. Diffraction gratings with periods down to around a few micrometers have been produced using metal (Al, Ag) nanoparticles with radii in the range of 70-100 nm. Moreover, several 2D devices, such as Fresnel zone plates, have been also produced showing the potential of the method. The diffractive particle patterns remain stable when light is removed. A method to transfer the diffractive patterns to other nonphotovoltaic substrates, such as silica glass, has been also reported.

Precision force sensing with optically-levitated nanospheres

Science.gov (United States)

Geraci, Andrew

2017-04-01

In high vacuum, optically-trapped dielectric nanospheres achieve excellent decoupling from their environment and experience minimal friction, making them ideal for precision force sensing. We have shown that 300 nm silica spheres can be used for calibrated zeptonewton force measurements in a standing-wave optical trap. In this optical potential, the known spacing of the standing wave anti-nodes can serve as an independent calibration tool for the displacement spectrum of the trapped particle. I will describe our progress towards using these sensors for tests of the Newtonian gravitational inverse square law at micron length scales. Optically levitated dielectric objects also show promise for a variety of other precision sensing applications, including searches for gravitational waves and other experiments in quantum optomechanics. National Science Foundation PHY-1205994, PHY-1506431, PHY-1509176.

Laser cooling and trapping of atoms

International Nuclear Information System (INIS)

Chu, S.

1995-01-01

The basic ideas of laser cooling and atom trapping will be discussed. These techniques have applications in spectroscopy, metrology, nuclear physics, biophysics, geophysics, and polymer science. (author)

Optical system for trapping particles in air.

Science.gov (United States)

Kampmann, R; Chall, A K; Kleindienst, R; Sinzinger, S

2014-02-01

An innovative optical system for trapping particles in air is presented. We demonstrate an optical system specifically optimized for high precision positioning of objects with a size of several micrometers within a nanopositioning and nanomeasuring machine (NPMM). Based on a specification sheet, an initial system design was calculated and optimized in an iterative design process. By combining optical design software with optical force simulation tools, a highly efficient optical system was developed. Both components of the system, which include a refractive double axicon and a parabolic ring mirror, were fabricated by ultra-precision turning. The characterization of the optical elements and the whole system, especially the force simulations based on caustic measurements, represent an important interim result for the subsequently performed trapping experiments. The caustic of the trapping beam produced by the system was visualized with the help of image processing techniques. Finally, we demonstrated the unique efficiency of the configuration by reproducibly trapping fused silica spheres with a diameter of 10 μm at a distance of 2.05 mm from the final optical surface.

Midgap traps related to compensation processes in CdTe alloys

International Nuclear Information System (INIS)

Castaldini, A.; Cavallini, A.; Fraboni, B.; Fernandez, P.; Piqueras, J.

1997-01-01

We study, by cathodoluminescence and junction spectroscopy methods, the deep traps located near midgap in semiconducting and semi-insulating II-VI compounds, namely, undoped CdTe, CdTe:Cl, and Cd 0.8 Zn 0.2 Te. In order to understand the role such deep levels play in the control of the electrical properties of the material, it appears necessary to determine their character, donor, or acceptor, in addition to their activation energy and capture cross section. Photoinduced-current transient spectroscopy and photo deep-level transient spectroscopy are used to investigate the semi-insulating (SI) samples, and a comparison of the complementary results obtained allows us to identify an acceptor trap, labeled H, and an electron trap, labeled E. Level H is common to all investigated compounds, while E is present only in CdTe:Cl samples. This provides clear experimental evidence of the presence of a deep trap in CdTe:Cl, which could be a good candidate for the deep donor level needed to explain the compensation process of SI CdTe:Cl. copyright 1997 The American Physical Society

High Precision Continuous and Real-Time Measurement of Atmospheric Oxygen Using Cavity Ring-Down Spectroscopy.

Science.gov (United States)

Kim-Hak, D.; Hoffnagle, J.; Rella, C.; Sun, M.

2016-12-01

Oxygen is a major and vital component of the Earth atmosphere representing about 21% of its composition. It is consumed or produced through biochemical processes such as combustion, respiration, and photosynthesis. Although atmospheric oxygen is not a greenhouse gas, it can be used as a top-down constraint on the carbon cycle. The variation observations of oxygen in the atmosphere are very small, in the order of the few ppm's. This presents the main technical challenge for measurement as a very high level of precision is required and only few methods including mass spectrometry, fuel cell, and paramagnetic are capable of overcoming it. Here we present new developments of a high-precision gas analyzer that utilizes the technique of Cavity Ring-Down Spectroscopy to measure oxygen concentration and oxygen isotope. Its compact and ruggedness design combined with high precision and long-term stability allows the user to deploy the instrument in the field for continuous monitoring of atmospheric oxygen level. Measurements have a 1-σ 5-minute averaging precision of 1-2 ppm for O2 over a dynamic range of 0-20%. We will present supplemental data acquired from our 10m tower measurements in Santa Clara, CA.

Status of THe-Trap

Energy Technology Data Exchange (ETDEWEB)

Streubel, Sebastian; Eronen, Tommi; Hoecker, Martin; Ketter, Jochen; Blaum, Klaus [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Van Dyck, Robert S. Jr. [Department of Physics, University of Washington, Seattle, WA (United States)

2013-07-01

THe-Trap (short for Tritium-{sup 3}He Trap) is a Penning-trap setup dedicated to measure the {sup 3}H to {sup 3}He mass-ratio with a relative uncertainty of better than 10{sup -11}. The ratio is of relevance for the KArlsruhe TRItium Neutrino experiment (KATRIN), which aims to measure the electron anti-neutrino mass, by measuring the shape of the β-decay energy spectrum close to its endpoint. An independent measurement of the {sup 3}H to {sup 3}He mass-ratio pins down this endpoint, and thus will help to determine the systematics of KATRIN. The trap setup consists of two Penning-traps: One trap for precision measurements, the other trap for ion storage. Ideally, the trap content will be periodically switched, which reduces the time between the measurements of the two ions' motional frequencies. In 2012, a mass ratio measurement of {sup 12}C{sup 4+} to {sup 14}N{sup 5+} was performed to characterize systematic effects of the traps. This measurement yielded a accuracy of 10{sup -9}. Further investigations revealed that a major reason for the modest accuracy is the large axial amplitude of ∼100 μm, compared to a ideal case of 3 μm at 4 K. In addition, relative magnetic fluctuations at a 3 x 10{sup -10} level on a 10 h timescale need to be significantly improved. In this contribution, the aforementioned findings and further systematic studies will be presented.

Near-infrared spectroscopy can reveal increases in brain activity related to animal-assisted therapy

OpenAIRE

Morita, Yuka; Ebara, Fumio; Morita, Yoshimitsu; Horikawa, Etsuo

2017-01-01

[Purpose] Previous studies have indicated that animal-assisted therapy can promote recovery of psychological, social, and physiological function in mental disorders. This study was designed as a pilot evaluation of the use of near-infrared spectroscopy to objectively identify changes in brain activity that could mediate the effect of animal-assisted therapy. [Subjects and Methods] The participants were 20 healthy students (10 males and 10 females; age 19?21 years) of the Faculty of Agricultur...

Cold highly charged ions in a cryogenic Paul trap

Energy Technology Data Exchange (ETDEWEB)

Versolato, O. O., E-mail: oscar.versolato@mpi-hd.mpg.de; Schwarz, M.; Windberger, A.; Ullrich, J. [Max-Planck-Institut fuer Kernphysik (Germany); Schmidt, P. O. [Physikalisch-Technische Bundesanstalt (Germany); Drewsen, M. [University of Aarhus, Department of Physics and Astronomy (Denmark); Crespo Lopez-Urrutia, J. R. [Max-Planck-Institut fuer Kernphysik (Germany)

2013-03-15

Narrow optical transitions in highly charged ions (HCIs) are of particular interest for metrology and fundamental physics, exploiting the high sensitivity of HCIs to new physics. The highest sensitivity for a changing fine structure constant ever predicted for a stable atomic system is found in Ir{sup 17 + }. However, laser spectroscopy of HCIs is hindered by the large ({approx} 10{sup 6} K) temperatures at which they are produced and trapped. An unprecedented improvement in such laser spectroscopy can be obtained when HCIs are cooled down to the mK range in a linear Paul trap. We have developed a cryogenic linear Paul trap in which HCIs will be sympathetically cooled by {sup 9}Be{sup + } ions. Optimized optical access for laser light is provided while maintaining excellent UHV conditions. The Paul trap will be connected to an electron beam ion trap (EBIT) which is able to produce a wide range of HCIs. This EBIT will also provide the first experimental input needed for the determination of the transition energies in Ir{sup 17 + }, enabling further laser-spectroscopic investigations of this promising HCI.

Electron trap annealing in neutron transmutation doped silicon

DEFF Research Database (Denmark)

Guldberg, J.

1977-01-01

Silicon doped by neutron transmutation to 1.2×1014 phosphorus atoms/cm3 was investigated with deep level transient spectroscopy using evaporated Au/n-Si diodes. Seven bulk electron traps were identified which appear after 30 min N2 anneal at temperatures between 425 and 725 °C. Five of these anne......Silicon doped by neutron transmutation to 1.2×1014 phosphorus atoms/cm3 was investigated with deep level transient spectroscopy using evaporated Au/n-Si diodes. Seven bulk electron traps were identified which appear after 30 min N2 anneal at temperatures between 425 and 725 °C. Five...

Progress at THe-trap

Energy Technology Data Exchange (ETDEWEB)

Hoecker, Martin; Eronen, Tommi; Ketter, Jochen; Schuh, Marc; Streubel, Sebastian; Blaum, Klaus [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Van Dyck, Robert S. Jr. [Department of Physics, University of Washington, Seattle, WA 98195-1560 (United States)

2014-07-01

THe-Trap is a Penning-trap mass spectrometry experiment that is currently being set up to measure the atomic mass ratio of tritium and helium-3 with a relative uncertainty of 10{sup -11}. In 2013, the experiment's first high-precision mass ratio measurement was performed on the ions {sup 12}C{sup 4+} and {sup 16}O{sup 5+}. The carbon-12/oxygen-16 mass ratio is one of the most precisely determined mass ratios and serves as a benchmark for the experiment. This measurement reached a statistical uncertainty of 6.3 . 10{sup -11} and was limited by systematic frequency shifts due to too high motional amplitudes. In the following service cycle, the experiment was modified to address the shortcomings that were discovered in the 2013 ratio measurements. This talk summarizes the results of the 2013 measurements and introduces the upgrades to the experiment, including a new amplifier, a modified ion source, and an improved vacuum system.

Towards Antihydrogen Confinement with the ALPHA Antihydrogen Trap

CERN Document Server

Fujiwara, M.C.; Bertsche, W.; Boston, A.; Bowe, P.D.; Cesar, C.L.; Chapman, S.; Charlton, M.; Chartier, M.; Deutsch, A.; Fajans, J.; Funakoshi, R.; Gill, D.R.; Gomberoff, K.; Hangst, J.S.; Hardy, W.N.; Hayano, R.S.; Hydomako, R.; Jenkins, M.J.; Jorgensen, L.V.; Kurchaninov, L.; Madsen, N.; Nolan, P.; Olchanski, K.; Olin, A.; Page, R.D.; Povilus, A.; Robicheaux, F.; Sarid, E.; Silveira, D.M.; Storey, J.W.; Thompson, R.I.; van der Werf, D.P.; Wurtele, J.S.; Yamazaki, Y.

2006-01-01

ALPHA is an international project that has recently begun experimentation at CERN's Antiproton Decelerator (AD) facility. The primary goal of ALPHA is stable trapping of cold antihydrogen atoms with the ultimate goal of precise spectroscopic comparisons with hydrogen. We discuss the status of the ALPHA project and the prospects for antihydrogen trapping.

Progress towards antihydrogen hyperfine spectroscopy in a beam

Energy Technology Data Exchange (ETDEWEB)

Widmann, Eberhard [Stefan Meyer Institute for Subatomic Physics, Vienna (Austria); Collaboration: ASACUSA CUSP collaboration

2014-07-01

The spectroscopy of antihydrogen promises one of the most precise tests of CPT symmetry. The ASACUSA CUSP collaboration at the Antiproton Decelerator of CERN is preparing an experiment to measure the ground-state hyperfine structure GS-HFS of antihydrogen, since this quantity is one of the most precisely determined transitions in ordinary hydrogen (relative accuracy ∝10{sup -12}). The experiment uses a Rabi-type atomic beam apparatus consisting of a source of spin-polarized antihydrogen (a so-called cusp trap), a microwave cavity to induce a spin flip, a superconducting sextuple magnet for spin analysis, and an antihydrogen detector. In this configuration, a relative accuracy of better than 10{sup -6} can be obtained. This precision will already allow to be sensitive to finite size effects of the antiproton, provided its magnetic moment will measured to higher precision, which is in progress by two collaborations at the AD. The recent progress in producing a beam of antihydrogen atoms and in the development of the apparatus as well as ways to further improve the accuracy by using the Ramsey method of separated oscillatory fields are presented.

Countering the stray magnetic field of the CUSP trap by using additional coils

CERN Document Server

Thole, Jelle

2016-01-01

The ASACUSA experiment at the Antiproton Decelerator (AD) at CERN tries to measure the Hyperfine Structure (HFS) of Antihydrogen (H ̄) using a Rabi spectroscopy set-up. In measuring this HFS it will yield a very precise test of CPT-symmetry. For this set-up to work a homogeneous magnetic field is needed in the cavity where the Hyperfine transition of H ̄ occurs. Due to the stray fields from the CUSP trap, where H ̄ is produced, additional coils are needed to counter these fields. It is found, using COMSOL simulations, that two coils are suitable for this. Leading to a relative standard deviation of the magnetic field of σB/B = 1.06%.

EBIT (Electron Beam Ion Trap), N-Division Experimental Physics. Annual report, 1994

Energy Technology Data Exchange (ETDEWEB)

Schneider, D. [ed.

1995-10-01

The experimental groups in the Electron Beam Ion Trap (EBIT) program continue to perform front-line research with trapped and extracted highly charged ions (HCI) in the areas of ion/surface interactions, atomic spectroscopy, electron-ion interaction and structure measurements, highly charged ion confinement, and EBIT development studies. The ion surface/interaction studies which were initiated five years ago have reached a stage where they an carry out routine investigations, as well as produce breakthrough results towards the development of novel nanotechnology. At EBIT and SuperEBIT studies of the x-ray emission from trapped ions continue to produce significant atomic structure data with high precision for few electron systems of high-Z ions. Furthermore, diagnostics development for magnetic and laser fusion, supporting research for the x-ray laser and weapons programs, and laboratory astrophysics experiments in support of NASA`s astrophysics program are a continuing effort. The two-electron contributions to the binding energy of helium like ions were measured for the first time. The results are significant because their precision is an order of magnitude better than those of competing measurements at accelerators, and the novel technique isolates the energy corrections that are the most interesting. The RETRAP project which was initiated three years ago has reached a stage where trapping, confining and electronic cooling of HCI ions up to Th{sup 80+} can be performed routinely. Measurements of the rates and cross sections for electron transfer from H{sub 2} performed to determine the lifetime of HCI up to Xe{sup q+} and Th{sup q+} (35 {le} q {le} 80) have been studied at mean energies estimated to be {approximately} 5 q eV. This combination of heavy ions with very high charges and very low energies is rare in nature, but may be encountered in planned fusion energy demonstration devices, in highly charged ion sources, or in certain astrophysical events.

Quantum optical emulation of molecular vibronic spectroscopy using a trapped-ion device.

Science.gov (United States)

Shen, Yangchao; Lu, Yao; Zhang, Kuan; Zhang, Junhua; Zhang, Shuaining; Huh, Joonsuk; Kim, Kihwan

2018-01-28

Molecules are one of the most demanding quantum systems to be simulated by quantum computers due to their complexity and the emergent role of quantum nature. The recent theoretical proposal of Huh et al. (Nature Photon., 9, 615 (2015)) showed that a multi-photon network with a Gaussian input state can simulate a molecular spectroscopic process. Here, we present the first quantum device that generates a molecular spectroscopic signal with the phonons in a trapped ion system, using SO 2 as an example. In order to perform reliable Gaussian sampling, we develop the essential experimental technology with phonons, which includes the phase-coherent manipulation of displacement, squeezing, and rotation operations with multiple modes in a single realization. The required quantum optical operations are implemented through Raman laser beams. The molecular spectroscopic signal is reconstructed from the collective projection measurements for the two-phonon-mode. Our experimental demonstration will pave the way to large-scale molecular quantum simulations, which are classically intractable, but would be easily verifiable by real molecular spectroscopy.

Coupling an optical trap to a mass separator

Energy Technology Data Exchange (ETDEWEB)

Chamberlin, E.P.; Sandberg, V.D.; Tupa, D.; Vieira, D.J.; Zhao, X.X. [Los Alamos National Lab., NM (United States); Guckert, R.; Wollnik, H. [Los Alamos National Lab., NM (United States)]/[Giessen Univ. (Germany); Preston, D.W. [Los Alamos National Lab., NM (United States)]/[California State Univ., Hayward, CA (United States)

1996-12-31

The efficient coupling of a magneto-optical trap to a mass separator is being developed to undertake high-precision electroweak interaction measurements in a series of radioisotopes. The use of ion implantation and subsequent heated-foil release is being pursued as a suitable way of introducing radioactive samples into the ultrahigh vacuum region of an optical trap without gas loading. This paper discusses the layout of the mass separator,the coupling to a magneto- optical trap, and the implantation and release scheme.

Coupling an optical trap to a mass separator

International Nuclear Information System (INIS)

Chamberlin, E.P.; Sandberg, V.D.; Tupa, D.; Vieira, D.J.; Zhao, X.X.; Guckert, R.; Wollnik, H.; Preston, D.W.

1996-01-01

The efficient coupling of a magneto-optical trap to a mass separator is being developed to undertake high-precision electroweak interaction measurements in a series of radioisotopes. The use of ion implantation and subsequent heated-foil release is being pursued as a suitable way of introducing radioactive samples into the ultrahigh vacuum region of an optical trap without gas loading. This paper discusses the layout of the mass separator,the coupling to a magneto- optical trap, and the implantation and release scheme

Spectroscopy of neutral radium

Energy Technology Data Exchange (ETDEWEB)

Mol, Aran; De, Subhadeep; Jungmann, Klaus; Wilschut, Hans; Willmann, Lorenz [KVI, University of Groningen, Groningen (Netherlands)

2008-07-01

The heavy alkaline earth atoms radium is uniquely sensitive towards parity and time reversal symmetry violations due to a large enhancement of an intrinsic permanent electric dipole moment of the nucleous or the electron. Furthermore, radium is sensitive to atomic parity violation and the nuclear anapole moment. To prepare such experiments spectroscopy of relevant atomic states need to be done. At a later stage we will build a neutral atom trap for radium. We have built an atomic beam of the short lived isotope {sup 225}Ra with a flux of several 10{sup 4} atoms/sec. We are preparing the laser spectroscopy using this beam setup. In the preparation for efficient laser cooling and trapping we have successfully trapped barium, which is similar in it's requirements for laser cooling. The techniques which we have developed with barium can be used to trap rare radium isotopes. We report on the progress of the experiments.

Overview of the current spectroscopy effort on the Livermore electron beam ion traps

International Nuclear Information System (INIS)

Beiersdorfer, P.; Lopez-Urrutia, J.C.; Brown, G.

1995-01-01

An overview is given of the current spectroscopic effort on the Livermore electron beam ion trap facilities. The effort focuses on four aspects: spectral line position, line intensity, temporal evolution, and line shape. Examples of line position measurements include studies of the K-shell transitions in heliumlike Kr 34+ and the 2s-2p intrashell transitions in lithiumlike Th 87+ and U 89+ , which provide benchmark values for testing the theory of relativistic and quantum electrodynamical contributions in high-Z ions. Examples of line intensity measurements are provided by measurements of the electron-impact excitation and dielectronic recombination cross sections of heliumlike transition-metal ions Ti 20+ through CO 25+ . A discussion of radiative lifetime measurements of metastable levels in heliumlike ions is given to illustrate the time-resolved spectroscopy techniques in the microsecond range. The authors also present a measurement of the spectral lineshape that illustrates the very low ion temperatures that can be achieved in an EBIT

Atomic physics measurements in an electron Beam Ion Trap

International Nuclear Information System (INIS)

Marrs, R.E.; Beiersdorfer, P.; Bennett, C.

1989-01-01

An electron Beam Ion Trap at Lawrence Livermore National Laboratory is being used to produce and trap very-highly-charged ions (q ≤ 70/+/) for x-ray spectroscopy measurements. Recent measurements of transition energies and electron excitation cross sections for x-ray line emission are summarized. 13 refs., 10 figs

Comparison of precision and speed in laparoscopic and robot-assisted surgical task performance.

Science.gov (United States)

Zihni, Ahmed; Gerull, William D; Cavallo, Jaime A; Ge, Tianjia; Ray, Shuddhadeb; Chiu, Jason; Brunt, L Michael; Awad, Michael M

2018-03-01

Robotic platforms have the potential advantage of providing additional dexterity and precision to surgeons while performing complex laparoscopic tasks, especially for those in training. Few quantitative evaluations of surgical task performance comparing laparoscopic and robotic platforms among surgeons of varying experience levels have been done. We compared measures of quality and efficiency of Fundamentals of Laparoscopic Surgery task performance on these platforms in novices and experienced laparoscopic and robotic surgeons. Fourteen novices, 12 expert laparoscopic surgeons (>100 laparoscopic procedures performed, no robotics experience), and five expert robotic surgeons (>25 robotic procedures performed) performed three Fundamentals of Laparoscopic Surgery tasks on both laparoscopic and robotic platforms: peg transfer (PT), pattern cutting (PC), and intracorporeal suturing. All tasks were repeated three times by each subject on each platform in a randomized order. Mean completion times and mean errors per trial (EPT) were calculated for each task on both platforms. Results were compared using Student's t-test (P task performance was slower on the robotic platform compared with laparoscopy. In comparisons of expert laparoscopists performing tasks on the laparoscopic platform and expert robotic surgeons performing tasks on the robotic platform, expert robotic surgeons demonstrated fewer errors during the PC task (P = 0.009). Robotic assistance provided a reduction in errors at all experience levels for some laparoscopic tasks, but no benefit in the speed of task performance. Robotic assistance may provide some benefit in precision of surgical task performance. Copyright © 2017 Elsevier Inc. All rights reserved.

Antihydrogen production and precision experiments

International Nuclear Information System (INIS)

Nieto, M.M.; Goldman, T.; Holzscheiter, M.H.

1996-01-01

The study of CPT invariance with the highest achievable precision in all particle sectors is of fundamental importance for physics. Equally important is the question of the gravitational acceleration of antimatter. In recent years, impressive progress has been achieved in capturing antiprotons in specially designed Penning traps, in cooling them to energies of a few milli-electron volts, and in storing them for hours in a small volume of space. Positrons have been accumulated in large numbers in similar traps, and low energy positron or positronium beams have been generated. Finally, steady progress has been made in trapping and cooling neutral atoms. Thus the ingredients to form antihydrogen at rest are at hand. Once antihydrogen atoms have been captured at low energy, spectroscopic methods can be applied to interrogate their atomic structure with extremely high precision and compare it to its normal matter counterpart, the hydrogen atom. Especially the 1S-2S transition, with a lifetime of the excited state of 122 msec and thereby a natural linewidth of 5 parts in 10 16 , offers in principle the possibility to directly compare matter and antimatter properties at a level of 1 part in 10 16

Precision electron polarimetry

International Nuclear Information System (INIS)

Chudakov, E.

2013-01-01

A new generation of precise Parity-Violating experiments will require a sub-percent accuracy of electron beam polarimetry. Compton polarimetry can provide such accuracy at high energies, but at a few hundred MeV the small analyzing power limits the sensitivity. Mo/ller polarimetry provides a high analyzing power independent on the beam energy, but is limited by the properties of the polarized targets commonly used. Options for precision polarimetry at 300 MeV will be discussed, in particular a proposal to use ultra-cold atomic hydrogen traps to provide a 100%-polarized electron target for Mo/ller polarimetry

Recombination in Perovskite Solar Cells : Significance of Grain Boundaries, Interface Traps, and Defect Ions

NARCIS (Netherlands)

Sherkar, Tejas; Momblona, Cristina; Gil-Escrig, Lidon; Avila, Jorge; Sessolo, Michele; Bolink, Henk J.; Koster, Lambert

2017-01-01

Trap-assisted recombination, despite being lower as compared with traditional inorganic solar cells, is still the dominant recombination mechanism in perovskite solar cells (PSCs) and limits their efficiency. We investigate the attributes of the primary trap-assisted recombination channels (grain

Controlling trapping potentials and stray electric fields in a microfabricated ion trap through design and compensation

International Nuclear Information System (INIS)

Charles Doret, S; Amini, Jason M; Wright, Kenneth; Volin, Curtis; Killian, Tyler; Ozakin, Arkadas; Denison, Douglas; Hayden, Harley; Pai, C-S; Slusher, Richart E; Harter, Alexa W

2012-01-01

Recent advances in quantum information processing with trapped ions have demonstrated the need for new ion trap architectures capable of holding and manipulating chains of many (>10) ions. Here we present the design and detailed characterization of a new linear trap, microfabricated with scalable complementary metal-oxide-semiconductor (CMOS) techniques, that is well-suited to this challenge. Forty-four individually controlled dc electrodes provide the many degrees of freedom required to construct anharmonic potential wells, shuttle ions, merge and split ion chains, precisely tune secular mode frequencies, and adjust the orientation of trap axes. Microfabricated capacitors on dc electrodes suppress radio-frequency pickup and excess micromotion, while a top-level ground layer simplifies modeling of electric fields and protects trap structures underneath. A localized aperture in the substrate provides access to the trapping region from an oven below, permitting deterministic loading of particular isotopic/elemental sequences via species-selective photoionization. The shapes of the aperture and radio-frequency electrodes are optimized to minimize perturbation of the trapping pseudopotential. Laboratory experiments verify simulated potentials and characterize trapping lifetimes, stray electric fields, and ion heating rates, while measurement and cancellation of spatially-varying stray electric fields permits the formation of nearly-equally spaced ion chains. (paper)

Light pionic atoms perspectives for precision experiments

International Nuclear Information System (INIS)

Gotta, D.

2005-01-01

During the last decades high-precision spectroscopy of exotic-atom x-rays profited in particular in the case of pions from the increasing number of stopped particles provided by the cyclotron trap at the accelerator facility of the Paul-Scherrer-Institut (PSI) together with modern detector concepts like charge-coupled devices (CCDs) and crystal spectrometers. Presently, priority is given to the study of the strong-interaction effects in the most elementary system - pionic hydrogen. However, the systems with two or more nucleons are as fundamental for the development of a theoretical description of hadronic matter. Furthermore, the de-excitation of exotic atoms involves a variety of atomic processes, which become accessible in detail due to the high resolution achievable with crystal spectrometers, e. g., parallel transitions, line splittings, broadenings and intensity distributions. In addition, first successful attempts for a microscopic description of the atomic cascade are available now, which should be subject to stringent tests both for atoms and molecules. (author)

Two photon spectroscopy of rubidium atoms in a magneto-optic trap

International Nuclear Information System (INIS)

Fretel, E.

1997-01-01

Two photon transitions without doppler effect can be used as an atomic reference. The aim of this work is to study two photon transitions of rubidium atoms in a magneto-optical trap. The chosen transition is from the level 5 2 S 1/2 toward the level 5 2 D 5/2 . The magneto-optical trap is achieved by using 3 pairs of perpendicular laser beams and by setting a magnetic field gradient. About 10 18 atoms are trapped and cooled in a 1 mm 3 volume. In a first stage we have realized an optical double resonance experiment from the level 5 2 S 1/2 toward the level 5 2 D 5/2 by populating the intermediate level 5 2 P 3/2 . Then we have studied the two photon transition in this cluster of cold atoms. A particular setting of the experiment allows to reduce the effect of ray broadening and shifting due to the magnetic field of the trap

Experiments with Highly-Ionized Atoms in Unitary Penning Traps

Directory of Open Access Journals (Sweden)

Shannon Fogwell Hoogerheide

2015-08-01

Full Text Available Highly-ionized atoms with special properties have been proposed for interesting applications, including potential candidates for a new generation of optical atomic clocks at the one part in 1019 level of precision, quantum information processing and tests of fundamental theory. The proposed atomic systems are largely unexplored. Recent developments at NIST are described, including the isolation of highly-ionized atoms at low energy in unitary Penning traps and the use of these traps for the precise measurement of radiative decay lifetimes (demonstrated with a forbidden transition in Kr17+, as well as for studying electron capture processes.

Direct observation of 0.57 eV trap-related RF output power reduction in AlGaN/GaN high electron mobility transistors

Science.gov (United States)

Arehart, A. R.; Sasikumar, A.; Rajan, S.; Via, G. D.; Poling, B.; Winningham, B.; Heller, E. R.; Brown, D.; Pei, Y.; Recht, F.; Mishra, U. K.; Ringel, S. A.

2013-02-01

This paper reports direct evidence for trap-related RF output power loss in GaN high electron mobility transistors (HEMTs) grown by metal organic chemical vapor deposition (MOCVD) through increased concentration of a specific electron trap at EC-0.57 eV that is located in the drain access region, as a function of accelerated life testing (ALT). The trap is detected by constant drain current deep level transient spectroscopy (CID-DLTS) and the CID-DLTS thermal emission time constant precisely matches the measured drain lag. Both drain lag and CID-DLTS measurements show this state to already exist in pre-stressed devices, which coupled with its strong increase in concentration as a function of stress in the absence of significant increases in concentrations of other detected traps, imply its role in causing degradation, in particular knee walkout. This study reveals EC-0.57 eV trap concentration tracks degradation induced by ALT for MOCVD-grown HEMTs supplied by several commercial and university sources. The results suggest this defect has a common source and may be a key degradation pathway in AlGaN/GaN HEMTs and/or an indicator to predict device lifetime.

HITRAP: A Facility for Experiments with Trapped Highly Charged Ions

International Nuclear Information System (INIS)

Quint, W.; Dilling, J.; Djekic, S.; Haeffner, H.; Hermanspahn, N.; Kluge, H.-J.; Marx, G.; Moore, R.; Rodriguez, D.; Schoenfelder, J.; Sikler, G.; Valenzuela, T.; Verdu, J.; Weber, C.; Werth, G.

2001-01-01

HITRAP is a planned ion trap facility for capturing and cooling of highly charged ions produced at GSI in the heavy-ion complex of the UNILAC-SIS accelerators and the ESR storage ring. In this facility heavy highly charged ions up to uranium will be available as bare nuclei, hydrogen-like ions or few-electron systems at low temperatures. The trap for receiving and studying these ions is designed for operation at extremely high vacuum by cooling to cryogenic temperatures. The stored highly charged ions can be investigated in the trap itself or can be extracted from the trap at energies up to about 10 keV/q. The proposed physics experiments are collision studies with highly charged ions at well-defined low energies (eV/u), high-accuracy measurements to determine the g-factor of the electron bound in a hydrogen-like heavy ion and the atomic binding energies of few-electron systems, laser spectroscopy of HFS transitions and X-ray spectroscopy

Precise mass measurements of exotic nuclei--the SHIPTRAP Penning trap mass spectrometer

International Nuclear Information System (INIS)

Herfurth, F.; Ackermann, D.; Block, M.; Dworschak, M.; Eliseev, S.; Hessberger, F.; Hofmann, S.; Kluge, H.-J.; Maero, G.; Martin, A.; Mazzocco, M.; Rauth, C.; Vorobjev, G.; Blaum, K.; Ferrer, R.; Neidherr, D.; Chaudhuri, A.; Marx, G.; Schweikhard, L.; Neumayr, J.

2007-01-01

The SHIPTRAP Penning trap mass spectrometer has been designed and constructed to measure the mass of short-lived, radioactive nuclei. The radioactive nuclei are produced in fusion-evaporation reactions and separated in flight with the velocity filter SHIP at GSI in Darmstadt. They are captured in a gas cell and transfered to a double Penning trap mass spectrometer. There, the cyclotron frequencies of the radioactive ions are determined and yield mass values with uncertainties ≥4.5·10 -8 . More than 50 nuclei have been investigated so far with the present overall efficiency of about 0.5 to 2%

Trapped antihydrogen

Energy Technology Data Exchange (ETDEWEB)

Butler, E., E-mail: eoin.butler@cern.ch [CERN, Physics Department (Switzerland); Andresen, G. B. [Aarhus University, Department of Physics and Astronomy (Denmark); Ashkezari, M. D. [Simon Fraser University, Department of Physics (Canada); Baquero-Ruiz, M. [University of California, Department of Physics (United States); Bertsche, W. [Swansea University, Department of Physics (United Kingdom); Bowe, P. D. [Aarhus University, Department of Physics and Astronomy (Denmark); Cesar, C. L. [Universidade Federal do Rio de Janeiro, Instituto de Fisica (Brazil); Chapman, S. [University of California, Department of Physics (United States); Charlton, M.; Deller, A.; Eriksson, S. [Swansea University, Department of Physics (United Kingdom); Fajans, J. [University of California, Department of Physics (United States); Friesen, T.; Fujiwara, M. C. [University of Calgary, Department of Physics and Astronomy (Canada); Gill, D. R. [TRIUMF (Canada); Gutierrez, A. [University of British Columbia, Department of Physics and Astronomy (Canada); Hangst, J. S. [Aarhus University, Department of Physics and Astronomy (Denmark); Hardy, W. N. [University of British Columbia, Department of Physics and Astronomy (Canada); Hayden, M. E. [Simon Fraser University, Department of Physics (Canada); Humphries, A. J. [Swansea University, Department of Physics (United Kingdom); Collaboration: ALPHA Collaboration; and others

2012-12-15

Precision spectroscopic comparison of hydrogen and antihydrogen holds the promise of a sensitive test of the Charge-Parity-Time theorem and matter-antimatter equivalence. The clearest path towards realising this goal is to hold a sample of antihydrogen in an atomic trap for interrogation by electromagnetic radiation. Achieving this poses a huge experimental challenge, as state-of-the-art magnetic-minimum atom traps have well depths of only {approx}1 T ({approx}0.5 K for ground state antihydrogen atoms). The atoms annihilate on contact with matter and must be 'born' inside the magnetic trap with low kinetic energies. At the ALPHA experiment, antihydrogen atoms are produced from antiprotons and positrons stored in the form of non-neutral plasmas, where the typical electrostatic potential energy per particle is on the order of electronvolts, more than 10{sup 4} times the maximum trappable kinetic energy. In November 2010, ALPHA published the observation of 38 antiproton annihilations due to antihydrogen atoms that had been trapped for at least 172 ms and then released-the first instance of a purely antimatter atomic system confined for any length of time (Andresen et al., Nature 468:673, 2010). We present a description of the main components of the ALPHA traps and detectors that were key to realising this result. We discuss how the antihydrogen atoms were identified and how they were discriminated from the background processes. Since the results published in Andresen et al. (Nature 468:673, 2010), refinements in the antihydrogen production technique have allowed many more antihydrogen atoms to be trapped, and held for much longer times. We have identified antihydrogen atoms that have been trapped for at least 1,000 s in the apparatus (Andresen et al., Nature Physics 7:558, 2011). This is more than sufficient time to interrogate the atoms spectroscopically, as well as to ensure that they have relaxed to their ground state.

Precision two-photon spectroscopy of alkali elements

Indian Academy of Sciences (India)

2014-07-18

Jul 18, 2014 ... A review of various techniques adopted for measuring absolute frequencies of the atomic transitions and precision measurements of isotope shifts and hyperfine structures (HFS) is presented. Some of the recent works on precision measurements of HFS constants of 6 2 S 1 / 2 level of 39 K and 41 K, 9 2 ...

Positional Accuracy in Optical Trap-Assisted Nanolithography

Science.gov (United States)

Arnold, Craig B.; McLeod, Euan

2009-03-01

The ability to directly print patterns on size scales below 100 nm is important for many applications where the production or repair of high resolution and density features are important. Laser-based direct-write methods have the benefit of quickly and easily being able to modify and create structures on existing devices, but feature sizes are conventionally limited by diffraction. In this presentation, we show how to overcome this limit with a new method of probe-based near-field nanopatterning in which we employ a CW laser to optically trap and manipulate dispersed microspheres against a substrate using a 2-d Bessel beam optical trap. A secondary, pulsed nanosecond laser at 355 nm is directed through the bead and used to modify the surface below the microsphere, taking advantage of the near-field enhancement in order to produce materials modification with feature sizes under 100 nm. Here, we analyze the 3-d positioning accuracy of the microsphere through analytic modeling as a function of experimental parameters. The model is verified in all directions for our experimental conditions and is used to predict the conditions required for improved positional accuracy.

Experimental characterization of the Hitrap Cooler trap with highly charged ions.

OpenAIRE

Fedotova, Svetlana

2013-01-01

The HITRAP (Highly charged Ions TRAP)facility is being set up and commissioned at GSI, Darmstadt. It will provide heavy, highly charged ions at low velocities to high-precision atomic physics experiments. Within this work the Cooler trap- the key element of the HITRAP facility was tested. The Cooler trap was assembled, aligned, and commissioned in trapping experiments with ions from off-line sources.The work performed within the scope of this thesis provided the baseline for further operation...

A constraint on antigravity of antimatter from precision spectroscopy of simple atoms

Science.gov (United States)

Karshenboim, S. G.

2009-10-01

Consideration of antigravity for antiparticles is an attractive target for various experimental projects. There are a number of theoretical arguments against it but it is not quite clear what kind of experimental data and theoretical suggestions are involved. In this paper we present straightforward arguments against a possibility of antigravity based on a few simple theoretical suggestions and some experimental data. The data are: astrophysical data on rotation of the Solar System in respect to the center of our galaxy and precision spectroscopy data on hydrogen and positronium. The theoretical suggestions for the case of absence of the gravitational field are: equality of electron and positron mass and equality of proton and positron charge. We also assume that QED is correct at the level of accuracy where it is clearly confirmed experimentally.

Trap-assisted and Langevin-type recombination in organic light-emitting diodes

NARCIS (Netherlands)

Wetzelaer, G. A. H.; Kuik, M.; Nicolai, H. T.; Blom, P. W. M.

2011-01-01

Trapping of charges is known to play an important role in the charge transport of organic semiconductors, but the role of traps in the recombination process has not been addressed. Here we show that the ideality factor of the current of organic light-emitting diodes (OLEDs) in the

Spectroscopy and nonclassical fluorescence properties of single trapped Ba+ ions

International Nuclear Information System (INIS)

Bolle, J.

1998-06-01

This thesis reports on the setup and application of an experimental apparatus for spectroscopic and quantum optical investigations of a single Barium ion in a Paul trap. The realization of the apparatus, which consists of the ion trap in ultra high vacuum, two laser systems, and a photon counting detection system, is described in detail, with particular consideration of the noise sources like stray light and laser frequency instabilities. The two lasers at 493 nm and 650 nm needed to continuously excite resonance fluorescence from the Barium ion have been realized using diode lasers only. The preparation of a single localized Barium ion is described, in particular its optical cooling with the laser light and the minimization of induced vibration in the trapping potential. The purely quantum mechanical property of antibunching is observed by measuring the intensity correlation function of resonance fluorescence from the trapped and cooled ion. Interference properties of the single ion resonance fluorescence are investigated with a Mach-Zehnder interferometer. From the measured high-contrast interference signal it is proven that each individual fluorescence photon interferes with itself. The fluorescence excitation spectrum, on varying one laser frequency, is also measured and exhibits dark resonances. These measurements are compared to calculations based on optical Bloch equations for the 8 atomic levels involved. Future experiments, in particular the detection of reduced quantum fluctuations (squeezing) in one quadrature component of the resonance fluorescence, are discussed. (author)

Laser tweezers: spectroscopy of optically trapped micron-sized particles

Energy Technology Data Exchange (ETDEWEB)

Kerr, K M; Livett, M K; Nugent, K W [Melbourne Univ., Parkville, VIC (Australia). School of Physics

1997-12-31

Information is often obtained about biological systems by analysis of single cells in the system. The optimum conditions for this analysis are when the cells are living and in their natural surroundings as they will be performing their normal functions and interactions. Analysis of cells can be difficult due to their mobility. Laser tweezing is a non contact method that can be employed to overcome this problem and provides a powerful tool in the analysis of functions and interactions at single cell level. In this investigation Raman spectra of a molecule of {beta} - carotene, dissolved in microdroplets of oil was obtained. The droplets were trapped using Nd-YAG beam and a low intensity Ar{sup +} beam was used to analyse the trapped particles. 2 refs., 5 figs.

Laser tweezers: spectroscopy of optically trapped micron-sized particles

Energy Technology Data Exchange (ETDEWEB)

Kerr, K.M.; Livett, M.K.; Nugent, K.W. [Melbourne Univ., Parkville, VIC (Australia). School of Physics

1996-12-31

Information is often obtained about biological systems by analysis of single cells in the system. The optimum conditions for this analysis are when the cells are living and in their natural surroundings as they will be performing their normal functions and interactions. Analysis of cells can be difficult due to their mobility. Laser tweezing is a non contact method that can be employed to overcome this problem and provides a powerful tool in the analysis of functions and interactions at single cell level. In this investigation Raman spectra of a molecule of {beta} - carotene, dissolved in microdroplets of oil was obtained. The droplets were trapped using Nd-YAG beam and a low intensity Ar{sup +} beam was used to analyse the trapped particles. 2 refs., 5 figs.

Ion bunch stacking in a Penning trap after purification in an electrostatic mirror trap

CERN Document Server

Rosenbusch, M; Blaum, K; Borgmann, Ch; Kreim, S; Lunney, D; Manea, V; Schweikhard, L; Wienholtz, F; Wolf, R N

2014-01-01

The success of many measurements in analytical mass spectrometry as well as in precision mass determinations for atomic and nuclear physics is handicapped when the ion sources deliver ``contaminations'', i.e., unwanted ions of masses similar to those of the ions of interest. In particular, in ion-trapping devices, large amounts of contaminant ions result in significant systematic errors-if the measurements are possible at all. We present a solution for such cases: The ions from a quasi-continuous source are bunched in a linear radio-frequency-quadrupole ion trap, separated by a multi-reflection time-of-flight section followed by a Bradbury-Nielsen gate, and then captured in a Penning trap. Buffer-gas cooling is used to damp the ion motion in the latter, which allows a repeated opening of the Penning trap for a stacking of mass-selected ion bunches. Proof-of-principle demonstrations have been performed with the ISOLTRAP setup at ISOLDE/CERN, both with Cs-133(+) ions from an off-line ion source and by applicati...

Studying antimatter with laser precision

CERN Multimedia

Katarina Anthony

2012-01-01

The next generation of antihydrogen trapping devices, ALPHA-2, is moving into CERN’s Antiproton Decelerator (AD) hall. This brand-new experiment will allow the ALPHA collaboration to conduct studies of antimatter with greater precision. ALPHA spokesperson Jeffrey Hangst was recently awarded a grant by the Carlsberg Foundation, which will be used to purchase equipment for the new experiment.   A 3-D view of the new magnet (in blue) and cryostat. The red lines show the paths of laser beams. LHC-type current leads for the superconducting magnets are visible on the top-right of the image. The ALPHA collaboration has been working to trap and study antihydrogen since 2006. Using antiprotons provided by CERN’s Antiproton Decelerator (AD), ALPHA was the first experiment to trap antihydrogen and to hold it long enough to study its properties. “The new ALPHA-2 experiment will use integrated lasers to probe the trapped antihydrogen,” explains Jeffrey Hangst, ALP...

Highly charged ion trapping and cooling

International Nuclear Information System (INIS)

Beck, B. R.; Church, D. A.; Gruber, L.; Holder, J. P.; Schneider, D.; Steiger, J.

1998-01-01

In the past few years a cryogenic Penning trap (RETRAP) has been operational at the Electron Beam Ion Trap (EBIT) facility at Lawrence Livermore National Laboratory. The combination of RETRAP and EBIT provides a unique possibility of producing and re-trapping highly charged ions and cooling them to very low temperatures. Due to the high Coulomb potentials in such an ensemble of cold highly charged ions the Coulomb coupling parameter (the ratio of Coulomb potential to the thermal energy) can easily reach values of 172 and more. To study such systems is not only of interest in astrophysics to simulate White Dwarf star interiors but opens up new possibilities in a variety of areas (e.g. laser spectroscopy), cold highly charged ion beams

A dominant electron trap in molecular beam epitaxial InAlN lattice-matched to GaN

Science.gov (United States)

Pandey, Ayush; Bhattacharya, Aniruddha; Cheng, Shaobo; Botton, Gianluigi A.; Mi, Zetian; Bhattacharya, Pallab

2018-04-01

Deep levels in lattice-matched undoped and Si-doped InAlN/GaN grown by plasma-assisted molecular beam epitaxy have been identified and characterized by capacitance and photocapacitance measurements. From x-ray diffraction, reflectance measurements, electron energy loss spectroscopy and high-resolution transmission electron microscopy it is evident that the material has two distinct phases with different compositions. These correspond to In compositions of 18.1% and 25.8%, with corresponding bandgaps of 4.6 eV and 4.1 eV, respectively. The lower bandgap material is present as columnar microstructures in the form of quantum wires. A dominant electron trap with an activation energy of 0.293  ±  0.01 eV, a small capture cross-section of (1.54  ±  0.25)  ×  10-18 cm2, and density increasing linearly with Si doping density is identified in all the samples. The characteristics of the electron trap and variation of diode capacitance are discussed in the context of carrier dynamics involving the dominant trap level and the quantum wires.

Deep level transient spectroscopy studies of charge traps introduced into silicon by channeling ion implantation of phosphorus

International Nuclear Information System (INIS)

McCallum, J.C.; Lay, M.; Deenapanray, P.N.K.; Jagadish, C.

2002-01-01

Full text: The operating conditions of a silicon-based quantum computer are expected to place stringent requirements on the quality of the material and the processes used to make it. In the Special Research Centre for Quantum Computer Technology, ion implantation is one of the principle processing techniques under investigation for forming an ordered array of phosphorus atoms. This technique introduces defect centres in silicon which act as charge traps. Charge traps are expected to be detrimental to operation of the device. These defect centres, their dependence on ion implantation and thermal annealing conditions are being quantified using Deep Level Transient Spectroscopy (DLTS). Since the aspect ratio of the masks required for the top-down fabrication process restrict the incident ions to a range of angles in which they may undergo channeling implantation in the silicon substrate, we have examined the effect of channeling implantation on the nature and quantity of the charge traps produced. This is the first time that DLTS studies have been performed for channeling implantation of a dopant species in silicon. DLTS is well-suited to the dose regime of ∼10 11 P/cm 3 required for the quantum computer, however, a standard DLTS measurement is unable to probe the shallow depth range of ∼ 20 nm required for the P atoms (∼ 10-15 keV implantation energy). Our aim has therefore been to perform P implants in the appropriate dose regime but using higher implantation energies, ∼ 75-450 keV, where DLTS can directly identify and profile the charge traps induced by the implantation step and monitor their annealing characteristics during subsequent processing. To map the behaviour observed in this energy regime onto the low energy range required for the quantum computer we are comparing the DLTS results to damage profiles predicted by the Monte Carlo code Crystal Trim which is used in the semiconductor industry to simulate ion implantation processes in crystalline

A Computer Model of Insect Traps in a Landscape

Science.gov (United States)

Manoukis, Nicholas C.; Hall, Brian; Geib, Scott M.

2014-11-01

Attractant-based trap networks are important elements of invasive insect detection, pest control, and basic research programs. We present a landscape-level, spatially explicit model of trap networks, focused on detection, that incorporates variable attractiveness of traps and a movement model for insect dispersion. We describe the model and validate its behavior using field trap data on networks targeting two species, Ceratitis capitata and Anoplophora glabripennis. Our model will assist efforts to optimize trap networks by 1) introducing an accessible and realistic mathematical characterization of the operation of a single trap that lends itself easily to parametrization via field experiments and 2) allowing direct quantification and comparison of sensitivity between trap networks. Results from the two case studies indicate that the relationship between number of traps and their spatial distribution and capture probability under the model is qualitatively dependent on the attractiveness of the traps, a result with important practical consequences.

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...

Microfabricated Microwave-Integrated Surface Ion Trap

Science.gov (United States)

Revelle, Melissa C.; Blain, Matthew G.; Haltli, Raymond A.; Hollowell, Andrew E.; Nordquist, Christopher D.; Maunz, Peter

2017-04-01

Quantum information processing holds the key to solving computational problems that are intractable with classical computers. Trapped ions are a physical realization of a quantum information system in which qubits are encoded in hyperfine energy states. Coupling the qubit states to ion motion, as needed for two-qubit gates, is typically accomplished using Raman laser beams. Alternatively, this coupling can be achieved with strong microwave gradient fields. While microwave radiation is easier to control than a laser, it is challenging to precisely engineer the radiated microwave field. Taking advantage of Sandia's microfabrication techniques, we created a surface ion trap with integrated microwave electrodes with sub-wavelength dimensions. This multi-layered device permits co-location of the microwave antennae and the ion trap electrodes to create localized microwave gradient fields and necessary trapping fields. Here, we characterize the trap design and present simulated microwave performance with progress towards experimental results. This research was funded, in part, by the Office of the Director of National Intelligence (ODNI), Intelligence Advanced Research Projects Activity (IARPA).

High precision γ spectroscopy of ΛΛ-Hypernuclei at the PANDA experiment

International Nuclear Information System (INIS)

Sanchez Lorente, A

2013-01-01

Hypernuclear research will be one of the main topics addressed by the PANDA experiment at FAIR at Darmstadt (Germany). Thanks to the use of stored antiproton beams, copious production of double ΛΛ-Hypernuclei is expected at the PANDA experiment, which will enable high precision gamma spectroscopy of such nuclei for the first time. At PANDA excited states of hypernuclei will be used as a starting point for the formation of double ΛΛ-Hypernuclei. In order to predict the yield of particle-stable double hypernuclei a microcanonical decay model was developed. For the detection of these nuclei, a devoted hypernuclear detector setup is planned. This set-up consists, in addition to the general purpose of the PANDA set-up, of a primary nuclear target for the production of pairs, a secondary active target for the hypernuclei formation and the identification of associated decay products and a germanium array detector to perform gamma spectroscopy. Moreover, one of the most challenging issues of this project is the fact that all detector systems need to operate in the presence of a high magnetic field and a large hadronic background. In these proceedings details concerning the identification procedure of double hypernuclei and the suppression of background will be presented. In addition, the current status of the activities related to the detector developments for this challenging programme will be briefly given.

Femtosecond Study of Self-Trapped Vibrational Excitons in Crystalline Acetanilide

Science.gov (United States)

Edler, J.; Hamm, P.; Scott, A. C.

2002-02-01

Femtosecond IR spectroscopy of delocalized NH excitations of crystalline acetanilide confirms that self-trapping in hydrogen-bonded peptide units exists and does stabilize the excitation. Two phonons with frequencies of 48 and 76 cm -1 are identified as the major degrees of freedom that mediate self-trapping. After selective excitation of the free exciton, self-trapping occurs within a few 100 fs. Excitation of the self-trapped states disappears from the spectral window of this investigation on a 1 ps time scale, followed by a slow ground state recovery of the hot ground state within 18 ps.

A robust single-beam optical trap for a gram-scale mechanical oscillator.

Science.gov (United States)

Altin, P A; Nguyen, T T-H; Slagmolen, B J J; Ward, R L; Shaddock, D A; McClelland, D E

2017-11-06

Precise optical control of microscopic particles has been mastered over the past three decades, with atoms, molecules and nano-particles now routinely trapped and cooled with extraordinary precision, enabling rapid progress in the study of quantum phenomena. Achieving the same level of control over macroscopic objects is expected to bring further advances in precision measurement, quantum information processing and fundamental tests of quantum mechanics. However, cavity optomechanical systems dominated by radiation pressure - so-called 'optical springs' - are inherently unstable due to the delayed dynamical response of the cavity. Here we demonstrate a fully stable, single-beam optical trap for a gram-scale mechanical oscillator. The interaction of radiation pressure with thermo-optic feedback generates damping that exceeds the mechanical loss by four orders of magnitude. The stability of the resultant spring is robust to changes in laser power and detuning, and allows purely passive self-locking of the cavity. Our results open up a new way of trapping and cooling macroscopic objects for optomechanical experiments.

The ALPHA Experiment a Cold Antihydrogen Trap

CERN Document Server

Bertsche, W; Bowe, P D; Cesar, C L; Chapman, S; Charlton, M; Chartier, M; Deutsch, A; Fajans, J; Fujiwara, M C; Funakoshi, R; Gill, D; Gomberoff, K; Grote, D P; Hangst, J S; Hayano, R S; Jenkins, M; Jørgensen, L V; Madsen, N; Miranda, D; Nolan, P; Ochanski, K; Olin, A; Page, R D; Posada, L G C; Robicheaux, F; Sarid, E; Telle, H H; Vay, J L; Wurtele, J; van der Werf, D P; Yamazaki, Y

2005-01-01

The ALPHA experiment aims to trap antihydrogen as the next crucial step towards a precise CPT test, by a spectroscopic comparison of antihydrogen with hydrogen. The experiment will retain the salient techniques developed by the ATHENA collaboration during the previous phase of antihydrogen experiments at the antiproton decelerator (AD) at CERN. The collaboration has identified the key problems in adding a neutral antiatom trap to the previously developed experimental configuration. The solutions identified by ALPHA are described in this paper.

A circularly polarized optical dipole trap and other developments in laser trapping of atoms

Science.gov (United States)

Corwin, Kristan Lee

Several innovations in laser trapping and cooling of alkali atoms are described. These topics share a common motivation to develop techniques for efficiently manipulating cold atoms. Such advances facilitate sensitive precision measurements such as parity non- conservation and 8-decay asymmetry in large trapped samples, even when only small quantities of the desired species are available. First, a cold, bright beam of Rb atoms is extracted from a magneto-optical trap (MOT) using a very simple technique. This beam has a flux of 5 × 109 atoms/s and a velocity of 14 m/s, and up to 70% of the atoms in the MOT were transferred to the atomic beam. Next, a highly efficient MOT for radioactive atoms is described, in which more than 50% of 221Fr atoms contained in a vapor cell are loaded into a MOT. Measurements were also made of the 221Fr 7 2P1/2 and 7 2P3/2 energies and hyperfine constants. To perform these experiments, two schemes for stabilizing the frequency of the light from a diode laser were developed and are described in detail. Finally, a new type of trap is described and a powerful cooling technique is demonstrated. The circularly polarized optical dipole trap provides large samples of highly spin-polarized atoms, suitable for many applications. Physical processes that govern the transfer of large numbers of atoms into the trap are described, and spin-polarization is measured to be 98(1)%. In addition, the trap breaks the degeneracy of the atomic spin states much like a magnetic trap does. This allows for RF and microwave cooling via both forced evaporation and a Sisyphus mechanism. Preliminary application of these techniques to the atoms in the circularly polarized dipole trap has successfully decreased the temperature by a factor of 4 while simultaneously increasing phase space density.

Simulation of I-V and C-V curves of metal/GaN/AlGaN/GaN heterostructures with trap-assisted tunnelling

International Nuclear Information System (INIS)

Racko, J.; Benko, P.; Grmanova, A.; Harmatha, L.; Breza, J.; Granzner, R.; Schwierz, F.

2013-01-01

The described trap-assisted tunnelling (TAT) model of the metal/GaN/Al_xGaN_1_-_x/GaN structure allows analyzing the effect of deep traps upon I-V and C-V characteristics. The negative charge with magnitude proportional to the molar concentration of aluminium gives rise to a barrier at the first heterojunction, which is higher than the Schottky barrier at the metal/GaN interface. On increasing the reverse bias Va the barrier at the first heterojunction is getting lower. The drop of this barrier causes an exponential increase of the reverse current. The current saturates, when the first heterojunction barrier is lower than the Schottky barrier. The effect of TAT can be observed also on varying the parameters of the band of traps. The shape of the simulated C-V curve is affected by changes in the charge on the second heterojunction. In principle it reflects the decrease of electron concentration in the quantum well on increasing the reverse bias V_a. The space charge region becomes wider and the electron concentration at the second heterojunction falls below the concentration of ionized deep trapping centres, which manifests itself as a noticeable drop in the capacitance of the metal/GaN/Al_xGaN_1_-_x/GaN structure. (authors)

Investigation of HIV-1 infected and uninfected cells using the optical trapping technique

CSIR Research Space (South Africa)

Ombinda-Lemboumba, Saturnin

2017-02-01

Full Text Available Optical trapping has emerged as an essential tool for manipulating single biological material and performing sophisticated spectroscopy analysis on individual cell. The optical trapping technique has been used to grab and immobilize cells from a...

Band Transport and Trapping in Didodecyl[1]benzothieno[3,2-b][1]benzothiophene Probed by Terahertz Spectroscopy.

Science.gov (United States)

Arend, Thomas R; Wimmer, Andreas; Schweicher, Guillaume; Chattopadhyay, Basab; Geerts, Yves H; Kersting, Roland

2017-11-02

Terahertz electromodulation spectroscopy provides insight into the material-inherent transport properties of charge carriers in organic semiconductors. Experiments on didodecyl[1]benzothieno[3,2-b][1]benzothiophene (C 12 -BTBT-C 12 ) devices yield for holes an intraband mobility of 9 cm 2 V -1 s -1 . The short duration of the THz pulses advances the understanding of the hole transport on the molecular scale. The efficient screening of Coulomb potentials leads to a collective response of the hole gas to external fields, which can be well described by the Drude model. Bias stress of the devices generates deep traps that capture mobile holes. Although the resulting polarization across the device hinders the injection of mobile holes, the hole mobilities are not affected.

Measurements and characterization of a hole trap in neutron-irradiated silicon

International Nuclear Information System (INIS)

Avset, B.S.

1996-04-01

The report describes measurements on a hole trap in neutron irradiated silicon diodes made one high resistivity phosphorus doped floatzone silicon. The hole trap was detected by Deep Level Transient Spectroscopy. This measurement gave a trap activation energy of 0.475 MeV. Other measurements showed that the trap has very small capture cross sections for both holes and electrons (10 -18 to 10 -20 cm 2 ) and that the hole capture cross section is temperature dependent. The energy level position of the trap has been estimated to be between 0.25 and 0.29 eV from the valence band. 25 refs., 21 figs., 4 tabs

Integrated microfluidic device for single-cell trapping and spectroscopy

KAUST Repository

Liberale, Carlo

2013-02-13

Optofluidic microsystems are key components towards lab-on-a-chip devices for manipulation and analysis of biological specimens. In particular, the integration of optical tweezers (OT) in these devices allows stable sample trapping, while making available mechanical, chemical and spectroscopic analyses.

Integrated microfluidic device for single-cell trapping and spectroscopy

KAUST Repository

Liberale, Carlo; Cojoc, G.; Bragheri, F.; Minzioni, P.; Perozziello, G.; La Rocca, R.; Ferrara, L.; Rajamanickam, V.; Di Fabrizio, Enzo M.; Cristiani, I.

2013-01-01

Optofluidic microsystems are key components towards lab-on-a-chip devices for manipulation and analysis of biological specimens. In particular, the integration of optical tweezers (OT) in these devices allows stable sample trapping, while making available mechanical, chemical and spectroscopic analyses.

Single florescent nanodiamond in a three dimensional ABEL trap

Science.gov (United States)

Kayci, Metin; Radenovic, Aleksandra

2015-01-01

Three dimensional single particle trapping and manipulation is an outstanding challenge in various fields ranging from basic physics to life sciences. By monitoring the response of a trapped particle to a designed environment one can extract its characteristics. In addition, quantum dynamics of a spatially scanned well-known particle can provide environmental information. Precise tracking and positioning of such a particle in aqueous environment is crucial task for achieving nano-scale resolution. Here we experimentally demonstrate three dimensional ABEL trap operating at high frequency by employing a hybrid approach in particle tracking. The particle location in the transverse plane is detected via a scanning laser beam while the axial position is determined by defocused imaging. The scanning of the trapped particle is accomplished through a nano positioning stage integrated to the trap platform. PMID:26559890

High-precision gamma-ray spectroscopy for enhancing production and application of medical isotopes

Science.gov (United States)

McCutchan, E. A.; Sonzogni, A. A.; Smith, S. V.; Muench, L.; Nino, M.; Greene, J. P.; Carpenter, M. P.; Zhu, S.; Chillery, T.; Chowdhury, P.; Harding, R.; Lister, C. J.

2015-10-01

Nuclear medicine is a field which requires precise decay data for use in planning radionuclide production and in imaging and therapeutic applications. To address deficiencies in decay data, sources of medical isotopes were produced and purified at the Brookhaven Linear Isotope Producer (BLIP) then shipped to Argonne National Laboratory where high-precision, gamma-ray measurements were performed using Gammasphere. New decay schemes for a number of PET isotopes and the impact on dose calculations will be presented. To investigate the production of next-generation theranostic or radiotherapeutic isotopes, cross section measurements with high energy protons have also been explored at BLIP. The 100-200 MeV proton energy regime is relatively unexplored for isotope production, thus offering high discovery potential but at the same time a challenging analysis due to the large number of open channels at these energies. Results of cross sections deduced from Compton-suppressed, coincidence gamma-ray spectroscopy performed at Lowell will be presented, focusing on the production of platinum isotopes by irradiating natural platinum foils with 100 to 200 MeV protons. DOE Isotope Program is acknowledged for funding ST5001030. Work supported by the US DOE under Grant DE-FG02-94ER40848 and Contracts DE-AC02-98CH10946 and DE-AC02-06CH11357.

Non-destructive Identification of Individual Leukemia Cells by Optical Trapping Raman Spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Chan, J W; Taylor, D S; Lane, S; Zwerdling, T; Tuscano, J; Huser, T

2007-03-05

Currently, a combination of technologies is typically required to assess the malignancy of cancer cells. These methods often lack the specificity and sensitivity necessary for early, accurate diagnosis. Here we demonstrate using clinical samples the application of laser trapping Raman spectroscopy as a novel approach that provides intrinsic biochemical markers for the noninvasive detection of individual cancer cells. The Raman spectra of live, hematopoietic cells provide reliable molecular fingerprints that reflect their biochemical composition and biology. Populations of normal T and B lymphocytes from four healthy individuals, and cells from three leukemia patients were analyzed, and multiple intrinsic Raman markers associated with DNA and protein vibrational modes have been identified that exhibit excellent discriminating power for cancer cell identification. A combination of two multivariate statistical methods, principal component analysis (PCA) and linear discriminant analysis (LDA), was used to confirm the significance of these markers for identifying cancer cells and classifying the data. The results indicate that, on average, 95% of the normal cells and 90% of the patient cells were accurately classified into their respective cell types. We also provide evidence that these markers are unique to cancer cells and not purely a function of differences in their cellular activation.

Development of a radiofrequency linear ion trap for {beta} decay study

Energy Technology Data Exchange (ETDEWEB)

Li, G. [McGill Univ., Montreal, Quebec (Canada); Argonne National Laboratory, Argonne, Illinois (United States); Scielzo, N.D. [Lawrence Livermore National Laboratory, Livermore, California (United States); Segel, R.E. [Northwestern Univ., Illinois (United States); and others

2010-07-01

A Beta decay Paul Trap (BPT) has been constructed at Argonne National Laboratory for the precise measurement of beta decay. We have demonstrated the capability of producing and transferring a low-energy, bunched, and isotopically pure ions beam. In BPT the ions are cooled to sub-eV energies, and confined in a volume of less than 1 mm{sup 3}. The trap has an open geometry which allows four sets of radiation detectors covering a substantial potion of solid angle. In combination with versatile detectors, BPT is able to precisely determine the entire decay kinematics of many isotopes. (author)

Progress in atomic spectroscopy

International Nuclear Information System (INIS)

Beyer, H.J.; Kleinpoppen, H.

1984-01-01

This book presents reviews by leading experts in the field covering areas of research at the forefront of atomic spectroscopy. Topics considered include the k ordering of atomic structure, multiconfiguration Hartree-Fock calculations for complex atoms, new methods in high-resolution laser spectroscopy, resonance ionization spectroscopy (inert atom detection), trapped ion spectroscopy, high-magnetic-field atomic physics, the effects of magnetic and electric fields on highly excited atoms, x rays from superheavy collision systems, recoil ion spectroscopy with heavy ions, investigations of superheavy quasi-atoms via spectroscopy of electron rays and positrons, impact ionization by fast projectiles, and amplitudes and state parameters from ion- and atom-atom excitation processes

Assessment of high precision, high accuracy Inductively Coupled Plasma-Optical Emission Spectroscopy to obtain concentration uncertainties less than 0.2% with variable matrix concentrations

International Nuclear Information System (INIS)

Rabb, Savelas A.; Olesik, John W.

2008-01-01

The ability to obtain high precision, high accuracy measurements in samples with complex matrices using High Performance Inductively Coupled Plasma-Optical Emission Spectroscopy (HP-ICP-OES) was investigated. The Common Analyte Internal Standard (CAIS) procedure was incorporated into the High Performance Inductively Coupled Plasma-Optical Emission Spectroscopy method to correct for matrix-induced changes in emission intensity ratios. Matrix matching and standard addition approaches to minimize matrix-induced errors when using High Performance Inductively Coupled Plasma-Optical Emission Spectroscopy were also assessed. The High Performance Inductively Coupled Plasma-Optical Emission Spectroscopy method was tested with synthetic solutions in a variety of matrices, alloy standard reference materials and geological reference materials

Trap-assisted transition between Schottky emission and Fowler-Nordheim tunneling in the interfacial-memristor based on Bi2S3 nano-networks

Directory of Open Access Journals (Sweden)

Ye Tian

2018-03-01

Full Text Available For the usage of the memristors in functional circuits, a predictive physical model is of great importance. However, other than the developments of the memristive models accounting bulky effects, the achievements on simulating the interfacial memristance are still insufficient. Here we provide a physical model to describe the electrical switching of the memristive interface. It considers the trap-assisted transition between Schottky emission and Fowler-Nordheim tunneling, and successfully reproduces the memristive behaviors occurring on the interface between Bi2S3 nano-networks and F-doped SnO2. Such success not only allows us uncover several features of the memristive interface including the distribution nature of the traps, barrier height/thickness and so on, but also provides a foundation from which we can quantitatively simulate the real interfacial memristor.

Co-existence of free and self-trapped excitons in J-aggregates

International Nuclear Information System (INIS)

Malyukin, Yu.V.; Lebedenko, A.N.; Sorokin, A.V.; Yefimova, S.L.

2005-01-01

Nature of excited electronic states of amphi-PIC J-aggregates, which are the source of the self-trapping states, have been investigated using low-temperature site-selective, time-resolved spectroscopy techniques. The self-trapping states are shown to evolve from the delocalized exciton states within the J-band. The strongly localized electronic states located on the low-frequency edge of the J-band, are not able to form polaronic states and, hence, the polaronic relaxation process is particularly collective one. The exciton self-trapping is more effective in J-aggregates with strong disorder, requires overcoming a self-trapping barrier

Optical trapping for analytical biotechnology.

Science.gov (United States)

Ashok, Praveen C; Dholakia, Kishan

2012-02-01

We describe the exciting advances of using optical trapping in the field of analytical biotechnology. This technique has opened up opportunities to manipulate biological particles at the single cell or even at subcellular levels which has allowed an insight into the physical and chemical mechanisms of many biological processes. The ability of this technique to manipulate microparticles and measure pico-Newton forces has found several applications such as understanding the dynamics of biological macromolecules, cell-cell interactions and the micro-rheology of both cells and fluids. Furthermore we may probe and analyse the biological world when combining trapping with analytical techniques such as Raman spectroscopy and imaging. Copyright © 2011 Elsevier Ltd. All rights reserved.

Impact of post deposition annealing in the electrically active traps at the interface between Ge(001) substrates and LaGeO{sub x} films grown by molecular beam deposition

Energy Technology Data Exchange (ETDEWEB)

Molle, Alessandro [Laboratorio MDM, CNR-IMM, via C. Olivetti 2, Agrate Brianza (MB) I-20864 (Italy); Baldovino, Silvia; Fanciulli, Marco [Laboratorio MDM, CNR-IMM, via C. Olivetti 2, Agrate Brianza (MB) I-20864 (Italy); Dipartimento di Scienza dei Materiali, Universita degli Studi di Milano Bicocca, Milano (Italy); Tsoutsou, Dimitra; Golias, Evangelos; Dimoulas, Athanasios [MBE Laboratory, Institute of Materials Science, NCSR DEMOKRITOS, Athens 153 10 (Greece)

2011-10-15

Changes in the electron trapping at the interface between Ge substrates and LaGeO{sub x} films grown by atomic O assisted molecular beam deposition are inferred upon post deposition annealing treatment on the as-deposited films from electrically detected magnetic resonance (EDMR) spectroscopy and from the electrical response of Pt/LaGeO{sub x}/Ge metal oxide semiconductor (MOS) capacitors. The improved electrical performance of the MOS capacitors upon annealing is consistent with the EDMR detected reduction of oxide defects which are associated with GeO species in the LaGeO{sub x} layer as evidenced by x-ray photoelectron spectroscopy.

Characterization of Cs vapor cell coated with octadecyltrichlorosilane using coherent population trapping spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Hafiz, Moustafa Abdel; Maurice, Vincent; Chutani, Ravinder; Passilly, Nicolas; Gorecki, Christophe; Boudot, Rodolphe [FEMTO-ST, CNRS, UFC, 26 Chemin de l' Epitaphe, 25030 Besançon Cedex (France); Guérandel, Stéphane; Clercq, Emeric de [LNE-SYRTE, Observatoire de Paris, CNRS, UPMC, 61 avenue de l' Observatoire, 75014 Paris (France)

2015-05-14

We report the realization and characterization using coherent population trapping (CPT) spectroscopy of an octadecyltrichlorosilane (OTS)-coated centimeter-scale Cs vapor cell. The dual-structure of the resonance lineshape, with presence of a narrow structure line at the top of a Doppler-broadened structure, is clearly observed. The linewidth of the narrow resonance is compared to the linewidth of an evacuated Cs cell and of a buffer gas Cs cell of similar size. The Cs-OTS adsorption energy is measured to be (0.42 ± 0.03) eV, leading to a clock frequency shift rate of 2.7 × 10{sup −9}/K in fractional unit. A hyperfine population lifetime, T{sub 1}, and a microwave coherence lifetime, T{sub 2}, of 1.6 and 0.5 ms are reported, corresponding to about 37 and 12 useful bounces, respectively. Atomic-motion induced Ramsey narrowing of dark resonances is observed in Cs-OTS cells by reducing the optical beam diameter. Ramsey CPT fringes are detected using a pulsed CPT interrogation scheme. Potential applications of the Cs-OTS cell to the development of a vapor cell atomic clock are discussed.

Characterization of Cs vapor cell coated with octadecyltrichlorosilane using coherent population trapping spectroscopy

International Nuclear Information System (INIS)

Hafiz, Moustafa Abdel; Maurice, Vincent; Chutani, Ravinder; Passilly, Nicolas; Gorecki, Christophe; Boudot, Rodolphe; Guérandel, Stéphane; Clercq, Emeric de

2015-01-01

We report the realization and characterization using coherent population trapping (CPT) spectroscopy of an octadecyltrichlorosilane (OTS)-coated centimeter-scale Cs vapor cell. The dual-structure of the resonance lineshape, with presence of a narrow structure line at the top of a Doppler-broadened structure, is clearly observed. The linewidth of the narrow resonance is compared to the linewidth of an evacuated Cs cell and of a buffer gas Cs cell of similar size. The Cs-OTS adsorption energy is measured to be (0.42 ± 0.03) eV, leading to a clock frequency shift rate of 2.7 × 10 −9 /K in fractional unit. A hyperfine population lifetime, T 1 , and a microwave coherence lifetime, T 2 , of 1.6 and 0.5 ms are reported, corresponding to about 37 and 12 useful bounces, respectively. Atomic-motion induced Ramsey narrowing of dark resonances is observed in Cs-OTS cells by reducing the optical beam diameter. Ramsey CPT fringes are detected using a pulsed CPT interrogation scheme. Potential applications of the Cs-OTS cell to the development of a vapor cell atomic clock are discussed

Dielectrophoretic trapping of multilayer DNA origami nanostructures and DNA origami-induced local destruction of silicon dioxide.

Science.gov (United States)

Shen, Boxuan; Linko, Veikko; Dietz, Hendrik; Toppari, J Jussi

2015-01-01

DNA origami is a widely used method for fabrication of custom-shaped nanostructures. However, to utilize such structures, one needs to controllably position them on nanoscale. Here we demonstrate how different types of 3D scaffolded multilayer origamis can be accurately anchored to lithographically fabricated nanoelectrodes on a silicon dioxide substrate by DEP. Straight brick-like origami structures, constructed both in square (SQL) and honeycomb lattices, as well as curved "C"-shaped and angular "L"-shaped origamis were trapped with nanoscale precision and single-structure accuracy. We show that the positioning and immobilization of all these structures can be realized with or without thiol-linkers. In general, structural deformations of the origami during the DEP trapping are highly dependent on the shape and the construction of the structure. The SQL brick turned out to be the most robust structure under the high DEP forces, and accordingly, its single-structure trapping yield was also highest. In addition, the electrical conductivity of single immobilized plain brick-like structures was characterized. The electrical measurements revealed that the conductivity is negligible (insulating behavior). However, we observed that the trapping process of the SQL brick equipped with thiol-linkers tended to induce an etched "nanocanyon" in the silicon dioxide substrate. The nanocanyon was formed exactly between the electrodes, that is, at the location of the DEP-trapped origami. The results show that the demonstrated DEP-trapping technique can be readily exploited in assembling and arranging complex multilayered origami geometries. In addition, DNA origamis could be utilized in DEP-assisted deformation of the substrates onto which they are attached. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A versatile electrostatic trap with open optical access

Science.gov (United States)

Li, Sheng-Qiang; Yin, Jian-Ping

2018-04-01

A versatile electrostatic trap with open optical access for cold polar molecules in weak-field-seeking state is proposed in this paper. The trap is composed of a pair of disk electrodes and a hexapole. With the help of a finite element software, the spatial distribution of the electrostatic field is calculated. The results indicate that a three-dimensional closed electrostatic trap is formed. Taking ND3 molecules as an example, the dynamic process of loading and trapping is simulated. The results show that when the velocity of the molecular beam is 10 m/s and the loading time is 0.9964 ms, the maximum loading efficiency reaches 94.25% and the temperature of the trapped molecules reaches about 30.3 mK. A single well can be split into two wells, which is of significant importance to the precision measurement and interference of matter waves. This scheme, in addition, can be further miniaturized to construct one-dimensional, two-dimensional, and three-dimensional spatial electrostatic lattices.

Modelling the influence of austenitisation temperature on hydrogen trapping in Nb containing martensitic steels

International Nuclear Information System (INIS)

Lang, Peter; Rath, Markus; Kozeschnik, Ernst; Rivera-Diaz-del-Castillo, Pedro E.J.

2015-01-01

Hydrogen trapping behaviour is investigated by means of thermokinetic simulations in a martensitic steel. The heat treatment consists of austenitisation followed by quenching and tempering. The model prescribes a minimum in hydrogen trapping at an austenitisation temperature of 1050 °C. Below this temperature, austenite grain boundaries are the prevailing trap, whereas niobium atoms in solid solution are the main traps above 1050 °C. The model describes precisely the experimental results

The Penning trap system used by the BASE experiment

CERN Multimedia

Marcastel, Fabienne

2015-01-01

A cut-away schematic of the Penning trap system used by BASE. The experiment receives antiprotons from CERN's AD; negative hydrogen ions are formed during injection into the apparatus. The set-up works with only a pair of particles at a time, while a cloud of a few hundred others are held in the reservoir trap, for future use. Here, an antiproton is in the measurement trap, while the negative hydyrogen ion is in held by the downstream park electrode. When the antiproton has been measured, it is moved to the upstream park electrode and the hydrogen ion is brought in to the measurement trap. This is repeated thousands of times, enabling a high-precision comparison of the charge-to-mass ratios of the two particles.

A Superconducting Magnet UCN Trap for Precise Neutron Lifetime Measurements.

Science.gov (United States)

Picker, R; Altarev, I; Bröcker, J; Gutsmiedl, E; Hartmann, J; Müller, A; Paul, S; Schott, W; Trinks, U; Zimmer, O

2005-01-01

Finite-element methods along with Monte Carlo simulations were used to design a magnetic storage device for ultracold neutrons (UCN) to measure their lifetime. A setup was determined which should make it possible to confine UCN with negligible losses and detect the protons emerging from β-decay with high efficiency: stacked superconducting solenoids create the magnetic storage field, an electrostatic extraction field inside the storage volume assures high proton collection efficiency. Alongside with the optimization of the magnetic and electrostatic design, the properties of the trap were investigated through extensive Monte Carlo simulation.

Real-time Detection of Antihydrogen Annihilations and Applications to Spectroscopy

Directory of Open Access Journals (Sweden)

Stracka Simone

2014-04-01

Full Text Available A detection scheme based on real-time measurement of antihydrogen annihilations during radiation injection is presented, which allows an efficient use of the trapped atoms for laser and microwave spectroscopy. The application of real-time detection of H¯$\\bar H$ annihilations to microwave spectroscopy, which yielded the first evidence of microwave induced spin-flip transitions in trapped antihydrogen [1], is reported.

Frequency-comb-assisted precision laser spectroscopy of CHF{sub 3} around 8.6 μm

Energy Technology Data Exchange (ETDEWEB)

Gambetta, Alessio; Coluccelli, Nicola; Cassinerio, Marco; Fernandez, Toney Teddy; Gatti, Davide; Laporta, Paolo; Galzerano, Gianluca, E-mail: gianluca.galzerano@polimi.it [Dipartimento di Fisica - Politecnico di Milano and Istituto di Fotonica e Nanotecnologie - CNR, Piazza Leonardo da Vinci 32, 20133 Milano (Italy); Castrillo, Antonio; Fasci, Eugenio; Gianfrani, Livio [Dipartimento di Matematica e Fisica - Seconda Università di Napoli, Viale Lincoln 5, 81100 Caserta (Italy); Ceausu-Velcescu, Adina [Laboratoire de Mathématiques et Physique, Université de Perpignan, Via Domitia EA 4217, F-66860 Perpignan (France); Santamaria, Luigi; Di Sarno, Valentina [CNR-INO, Istituto Nazionale di Ottica, Via Campi Flegrei 34, 80078 Pozzuoli, NA (Italy); Maddaloni, Pasquale [CNR-INO, Istituto Nazionale di Ottica, Via Campi Flegrei 34, 80078 Pozzuoli, NA (Italy); INFN, Istituto Nazionale di Fisica Nucleare, Sez. Firenze, Via G. Sansone 1, 50019 Sesto Fiorentino, FI (Italy); De Natale, Paolo [INFN, Istituto Nazionale di Fisica Nucleare, Sez. Firenze, Via G. Sansone 1, 50019 Sesto Fiorentino, FI (Italy); CNR-INO, Istituto Nazionale di Ottica, Largo E. Fermi 6, 50125 Firenze (Italy)

2015-12-21

We report a high-precision spectroscopic study of room-temperature trifluoromethane around 8.6 μm, using a CW quantum cascade laser phase-locked to a mid-infrared optical frequency comb. This latter is generated by a nonlinear down-conversion process starting from a dual-branch Er:fiber laser and is stabilized against a GPS-disciplined rubidium clock. By tuning the comb repetition frequency, several transitions falling in the υ{sub 5} vibrational band are recorded with a frequency resolution of 20 kHz. Due to the very dense spectra, a special multiple-line fitting code, involving a Voigt profile, is developed for data analysis. The combination of the adopted experimental approach and survey procedure leads to fractional accuracy levels in the determination of line center frequencies, down to 2 × 10{sup −10}. Line intensity factors, pressure broadening, and shifting parameters are also provided.

Precision atomic beam density characterization by diode laser absorption spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Oxley, Paul; Wihbey, Joseph [Physics Department, The College of the Holy Cross, Worcester, Massachusetts 01610 (United States)

2016-09-15

We provide experimental and theoretical details of a simple technique to determine absolute line-of-sight integrated atomic beam densities based on resonant laser absorption. In our experiments, a thermal lithium beam is chopped on and off while the frequency of a laser crossing the beam at right angles is scanned slowly across the resonance transition. A lock-in amplifier detects the laser absorption signal at the chop frequency from which the atomic density is determined. The accuracy of our experimental method is confirmed using the related technique of wavelength modulation spectroscopy. For beams which absorb of order 1% of the incident laser light, our measurements allow the beam density to be determined to an accuracy better than 5% and with a precision of 3% on a time scale of order 1 s. Fractional absorptions of order 10{sup −5} are detectable on a one-minute time scale when we employ a double laser beam technique which limits laser intensity noise. For a lithium beam with a thickness of 9 mm, we have measured atomic densities as low as 5 × 10{sup 4} atoms cm{sup −3}. The simplicity of our technique and the details we provide should allow our method to be easily implemented in most atomic or molecular beam apparatuses.

Precision atomic beam density characterization by diode laser absorption spectroscopy

International Nuclear Information System (INIS)

Oxley, Paul; Wihbey, Joseph

2016-01-01

We provide experimental and theoretical details of a simple technique to determine absolute line-of-sight integrated atomic beam densities based on resonant laser absorption. In our experiments, a thermal lithium beam is chopped on and off while the frequency of a laser crossing the beam at right angles is scanned slowly across the resonance transition. A lock-in amplifier detects the laser absorption signal at the chop frequency from which the atomic density is determined. The accuracy of our experimental method is confirmed using the related technique of wavelength modulation spectroscopy. For beams which absorb of order 1% of the incident laser light, our measurements allow the beam density to be determined to an accuracy better than 5% and with a precision of 3% on a time scale of order 1 s. Fractional absorptions of order 10 −5 are detectable on a one-minute time scale when we employ a double laser beam technique which limits laser intensity noise. For a lithium beam with a thickness of 9 mm, we have measured atomic densities as low as 5 × 10 4 atoms cm −3 . The simplicity of our technique and the details we provide should allow our method to be easily implemented in most atomic or molecular beam apparatuses.

Precision atomic beam density characterization by diode laser absorption spectroscopy.

Science.gov (United States)

Oxley, Paul; Wihbey, Joseph

2016-09-01

We provide experimental and theoretical details of a simple technique to determine absolute line-of-sight integrated atomic beam densities based on resonant laser absorption. In our experiments, a thermal lithium beam is chopped on and off while the frequency of a laser crossing the beam at right angles is scanned slowly across the resonance transition. A lock-in amplifier detects the laser absorption signal at the chop frequency from which the atomic density is determined. The accuracy of our experimental method is confirmed using the related technique of wavelength modulation spectroscopy. For beams which absorb of order 1% of the incident laser light, our measurements allow the beam density to be determined to an accuracy better than 5% and with a precision of 3% on a time scale of order 1 s. Fractional absorptions of order 10 -5 are detectable on a one-minute time scale when we employ a double laser beam technique which limits laser intensity noise. For a lithium beam with a thickness of 9 mm, we have measured atomic densities as low as 5 × 10 4 atoms cm -3 . The simplicity of our technique and the details we provide should allow our method to be easily implemented in most atomic or molecular beam apparatuses.

Trapped charged particles a graduate textbook with problems and solutions

CERN Document Server

Madsen, Niels; Thompson, Richard C

2016-01-01

At Les Houches in January 2015, experts in the field of particle trapping came together to discuss the fundamental physics of traps and the different types of applications. This textbook collates the lectures delivered there; the Second Winter School on Physics with Trapped Charged Particles. Taken as a whole, the book gives an overview of why traps for charged particles are important, how they work, their special features and limitations, and their application in areas such as precision measurements, mass spectrometry, optical clocks, plasma physics, antihydrogen creation, quantum simulation and quantum information processing. Chapters from various world experts include those on the basic properties of Penning traps, RF traps and particle accelerators, as well as those covering important practical aspects such as vacuum systems, detection techniques, and different types of particle cooling including laser cooling. Finally, individual chapters deal with the different areas of application listed above. Each ...

Hydrogenation of the ``new oxygen donor'' traps in silicon

Science.gov (United States)

Hölzlein, K.; Pensl, G.; Schulz, M.; Johnson, N. M.

1986-04-01

Hydrogenation was performed at moderate temperatures (≤300 °C) on Czochralski-grown Si samples that contained high concentrations of the oxygen-related ``new donor'' (ND) traps. From deep level transient spectroscopy, a comparison of spectra from untreated reference and hydrogenated material reveals that two different types of defect states contribute to the continuous energy distribution of the ND traps. The experimental and theoretical results further establish the ``SiOx interface'' model for the ND defects.

Weak Interaction Measurements with Optically Trapped Radioactive Atoms

International Nuclear Information System (INIS)

Vieira, D.J.; Crane, S.G.; Guckert, R.; Zhao, X.; Brice, S.J.; Goldschmidt, A.; Hime, A.; Tupa, D.

1999-01-01

This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The goal of this project is to apply the latest in magneto-optical and pure magnetic trapping technology to concentrate, cool, confine, and polarize radioactive atoms for precise electroweak interaction measurements. In particular, the authors have concentrated their efforts on the trapping of 82 Rb for a parity-violating, beta-asymmetry measurement. Progress has been made in successfully trapping of up to 6 million 82 Rb(t 1/2 =75s) atoms in a magneto-optical trap coupled to a mass separator. This represents a two order of magnitude improvement in the number trapped radioactive atoms over all previous work. They have also measured the atomic hyperfine structure of 82 Rb and demonstrated the MOT-to-MOT transfer and accumulation of atoms in a second trap. Finally, they have constructed and tested a time-orbiting-potential magnetic trap that will serve as a rotating beacon of spin-polarized nuclei and a beta-telescope detection system. Prototype experiments are now underway with the initial goal of making a 1% measurements of the beta-asymmetry parameter A which would match the world's best measurements

Physical and chemical study of single aerosol particles using optical trapping cavity ringdown spectroscopy

Science.gov (United States)

2016-08-30

scope that views the trapped particle walking through the ringdown beam step by step. (b) An image that shows the traces of the particle (MWCNT... walking through the RD beam . 5 a b c Fig.3 The OT-CRDS single particle scope views oscillations of a trapped particle. (a) Image of a trapped...and walking single carbon- nanotube particles of ?50 µm in size and viewing those properties via changes of ringdown time. This single- aerosol

Electron plasmas as a diagnostic tool for hyperfine spectroscopy of antihydrogen

Energy Technology Data Exchange (ETDEWEB)

Friesen, T.; Thompson, R. I. [Department of Physics and Astronomy, University of Calgary, Calgary AB, T2N 1N4 (Canada); Amole, C.; Capra, A.; Menary, S. [Department of Physics and Astronomy, York University, Toronto ON, M3J 1P3 (Canada); Ashkezari, M. D.; Hayden, M. E. [Department of Physics, Simon Fraser University, Burnaby BC, V5A 1S6 (Canada); Baquero-Ruiz, M.; Fajans, J.; Little, A.; So, C.; Wurtele, J. S. [Department of Physics, University of California, Berkeley, CA 94720-7300 (United States); Bertsche, W. [School of Physics and Astronomy, University of Manchester, M13 9PL Manchester, UK and The Cockcroft Institute, WA4 4AD Warrington (United Kingdom); Bowe, P. D.; Hangst, J. S.; Rasmussen, C. O. [Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C (Denmark); Butler, E. [Physics Department, CERN, CH-1211 Geneva 23 (Switzerland); Cesar, C. L.; Silveira, D. M. [Instituto de Fisica, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-972 (Brazil); Charlton, M. [Department of Physics, College of Science, Swansea University, Swansea SA2 8PP (United Kingdom); and others

2013-03-19

Long term magnetic confinement of antihydrogen atoms has recently been demonstrated by the ALPHA collaboration at CERN, opening the door to a range of experimental possibilities. Of particular interest is a measurement of the antihydrogen spectrum. A precise comparison of the spectrum of antihydrogen with that of hydrogen would be an excellent test of CPT symmetry. One prime candidate for precision CPT tests is the ground-state hyperfine transition; measured in hydrogen to a precision of nearly one part in 10{sup 12}. Effective execution of such an experiment with trapped antihydrogen requires precise knowledge of the magnetic environment. Here we present a solution that uses an electron plasma confined in the antihydrogen trapping region. The cyclotron resonance of the electron plasma is probed with microwaves at the cyclotron frequency and the subsequent heating of the electron plasma is measured through the plasma quadrupole mode frequency. Using this method, the minimum magnetic field of the neutral trap can be determined to within 4 parts in 10{sup 4}. This technique was used extensively in the recent demonstration of resonant interaction with the hyperfine levels of trapped antihydrogen atoms.

Observation of Spin Flips with a Single Trapped Proton

CERN Document Server

Ulmer, S.; Blaum, K.; Kracke, H.; Mooser, A.; Quint, W.; Walz, J.

2011-01-01

Spin transitions of an isolated trapped proton are observed for the first time. The spin quantum jumps are detected via the continuous Stern-Gerlach effect which is used in an experiment with a single proton stored in a cryogenic Penning trap. This opens the way for a direct high-precision measurement of the magnetic moment of the proton and a new test of the matter-antimatter symmetry in the baryon sector. This method can also be applied to other light atomic nuclei.

Call for papers for special issue of Journal of Molecular Spectroscopy focusing on "Frequency-comb spectroscopy"

Science.gov (United States)

Foltynowicz, Aleksandra; Picqué, Nathalie; Ye, Jun

2018-05-01

Frequency combs are becoming enabling tools for many applications in science and technology, beyond the original purpose of frequency metrology of simple atoms. The precisely evenly spaced narrow lines of a laser frequency comb inspire intriguing approaches to molecular spectroscopy, designed and implemented by a growing community of scientists. Frequency-comb spectroscopy advances the frontiers of molecular physics across the entire electro-magnetic spectrum. Used as frequency rulers, frequency combs enable absolute frequency measurements and precise line shape studies of molecular transitions, for e.g. tests of fundamental physics and improved determination of fundamental constants. As light sources interrogating the molecular samples, they dramatically improve the resolution, precision, sensitivity and acquisition time of broad spectral-bandwidth spectroscopy and open up new opportunities and applications at the leading edge of molecular spectroscopy and sensing.

A novel ion cooling trap for multi-reflection time-of-flight mass spectrograph

Energy Technology Data Exchange (ETDEWEB)

Ito, Y., E-mail: yito@riken.jp [SLOWRI Team, Nishina Accelerator-Based Research Center, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577 (Japan); Schury, P. [SLOWRI Team, Nishina Accelerator-Based Research Center, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577 (Japan); New Mexico State University, Department Chemistry and Biochemistry, Las Cruces, NM 88003 (United States); Wada, M.; Naimi, S. [SLOWRI Team, Nishina Accelerator-Based Research Center, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Smorra, C. [SLOWRI Team, Nishina Accelerator-Based Research Center, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany); Sonoda, T. [SLOWRI Team, Nishina Accelerator-Based Research Center, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Mita, H. [SLOWRI Team, Nishina Accelerator-Based Research Center, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577 (Japan); Takamine, A. [SLOWRI Team, Nishina Accelerator-Based Research Center, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Aoyama Gakuin University, 4-4-25 Shibuya, Shibuya-ku, Tokyo 150-8366 (Japan); Okada, K. [SLOWRI Team, Nishina Accelerator-Based Research Center, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Sophia University, 7-1 Kioi-cho, Chiyoda-ku, Tokyo 102-8554 (Japan); Ozawa, A. [University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577 (Japan); Wollnik, H. [SLOWRI Team, Nishina Accelerator-Based Research Center, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); New Mexico State University, Department Chemistry and Biochemistry, Las Cruces, NM 88003 (United States)

2013-12-15

Highlights: • Fast cooling time: 2 ms. • High efficiency: ≈27% for {sup 23}Na{sup +} and ≈5.1% for {sup 7}Li{sup +}. • 100% Duty cycle with double trap system. -- Abstract: A radiofrequency quadrupole ion trap system for use with a multi-reflection time-of-flight mass spectrograph (MRTOF) for short-lived nuclei has been developed. The trap system consists of two different parts, an asymmetric taper trap and a flat trap. The ions are cooled to a sufficient small bunch for precise mass measurement with MRTOF in only 2 ms cooling time in the flat trap, then orthogonally ejected to the MRTOF for mass analysis. A trapping efficiency of ≈27% for {sup 23}Na{sup +} and ≈5.1% for {sup 7}Li{sup +} has been achieved.

Laser Cooling and Trapping of Neutral Strontium for Spectroscopic Measurements of Casimir-Polder Potentials

Science.gov (United States)

Cook, Eryn C.

Casimir and Casimir-Polder effects are forces between electrically neutral bodies and particles in vacuum, arising entirely from quantum fluctuations. The modification to the vacuum electromagnetic-field modes imposed by the presence of any particle or surface can result in these mechanical forces, which are often the dominant interaction at small separations. These effects play an increasingly critical role in the operation of micro- and nano-mechanical systems as well as miniaturized atomic traps for precision sensors and quantum-information devices. Despite their fundamental importance, calculations present theoretical and numeric challenges, and precise atom-surface potential measurements are lacking in many geometric and distance regimes. The spectroscopic measurement of Casimir-Polder-induced energy level shifts in optical-lattice trapped atoms offers a new experimental method to probe atom-surface interactions. Strontium, the current front-runner among optical frequency metrology systems, has demonstrated characteristics ideal for such precision measurements. An alkaline earth atom possessing ultra-narrow intercombination transitions, strontium can be loaded into an optical lattice at the "magic" wavelength where the probe transition is unperturbed by the trap light. Translation of the lattice will permit controlled transport of tightly-confined atomic samples to well-calibrated atom-surface separations, while optical transition shifts serve as a direct probe of the Casimir-Polder potential. We have constructed a strontium magneto-optical trap (MOT) for future Casimir-Polder experiments. This thesis will describe the strontium apparatus, initial trap performance, and some details of the proposed measurement procedure.

Sampling density for the quantitative evaluation of air trapping

International Nuclear Information System (INIS)

Goris, Michael L.; Robinson, Terry E.

2009-01-01

Concerns have been expressed recently about the radiation burden on patient populations, especially children, undergoing serial radiological testing. To reduce the dose one can change the CT acquisition settings or decrease the sampling density. In this study we determined the minimum desirable sampling density to ascertain the degree of air trapping in children with cystic fibrosis. Ten children with cystic fibrosis in stable condition underwent a volumetric spiral CT scan. The degree of air trapping was determined by an automated algorithm for all slices in the volume, and then for 1/2, 1/4, to 1/128 of all slices, or a sampling density ranging from 100% to 1% of the total volume. The variation around the true value derived from 100% sampling was determined for all other sampling densities. The precision of the measurement remained stable down to a 10% sampling density, but decreased markedly below 3.4%. For a disease marker with the regional variability of air trapping in cystic fibrosis, regardless of observer variability, a sampling density below 10% and even more so, below 3.4%, apparently decreases the precision of the evaluation. (orig.)

Quantitative optical trapping and optical manipulation of micro-sized objects

Directory of Open Access Journals (Sweden)

Rania Sayed

2017-10-01

Full Text Available An optical tweezers technique is used for ultraprecise micromanipulation to measure positions of micrometer scale objects with a precision down to the nanometer scale. It consists of a high performance research microscope with motorized scanning stage and sensitive position detection system. Up to 10 traps can be used quasi-simultaneously. Non photodamage optical trapping of Escherichia coli (E. coli bacteria cells of 2 µm in length, as an example of motile bacteria, has been shown in this paper. Also, efficient optical trapping and rotation of polystyrene latex particles of 3 µm in diameter have been studied, as an optical handle for the pick and place of other tiny objects. A fast galvoscanner is used to produce multiple optical traps for manipulation of micro-sized objects and optical forces of these trapped objects quantified and measured according to explanation of ray optics regime. The diameter of trapped particle is bigger than the wavelength of the trapping laser light. The force constant (k has been determined in real time from the positional time series recorded from the trapped object that is monitored by a CCD camera through a personal computer.

An Ingenious Super Light Trapping Surface Templated from Butterfly Wing Scales

Science.gov (United States)

Han, Zhiwu; Li, Bo; Mu, Zhengzhi; Yang, Meng; Niu, Shichao; Zhang, Junqiu; Ren, Luquan

2015-08-01

Based on the super light trapping property of butterfly Trogonoptera brookiana wings, the SiO2 replica of this bionic functional surface was successfully synthesized using a simple and highly effective synthesis method combining a sol-gel process and subsequent selective etching. Firstly, the reflectivity of butterfly wing scales was carefully examined. It was found that the whole reflectance spectroscopy of the butterfly wings showed a lower level (less than 10 %) in the visible spectrum. Thus, it was confirmed that the butterfly wings possessed a super light trapping effect. Afterwards, the morphologies and detailed architectures of the butterfly wing scales were carefully investigated using the ultra-depth three-dimensional (3D) microscope and field emission scanning electronic microscopy (FESEM). It was composed by the parallel ridges and quasi-honeycomb-like structure between them. Based on the biological properties and function above, an exact SiO2 negative replica was fabricated through a synthesis method combining a sol-gel process and subsequent selective etching. At last, the comparative analysis of morphology feature size and the reflectance spectroscopy between the SiO2 negative replica and the flat plate was conducted. It could be concluded that the SiO2 negative replica inherited not only the original super light trapping architectures, but also the super light trapping characteristics of bio-template. This work may open up an avenue for the design and fabrication of super light trapping materials and encourage people to look for more super light trapping architectures in nature.

First observation of spin flips with a single proton stored in a cryogenic Penning trap

International Nuclear Information System (INIS)

Ulmer, Stefan

2011-01-01

In this thesis the very first observation of spin transitions of a single proton stored in a cryogenic double-Penning trap is presented. The experimental observation of spin transitions is based on the continuous Stern-Gerlach effect, which couples the spin of the single trapped proton to its axial eigenfrequency, by means of an inhomogeneous magnetic field. A spin transition causes a change of the axial frequency, which can be measured non-destructively. Due to the tiny magnetic moment of the proton, the direct detection of proton spin-flips is an exceeding challenge. To achieve spin-flip resolution, the proton was stored in the largest magnetic field inhomogeneity, which has ever been superimposed to a Penning trap, and its axial frequency was detected non-destructively. Therefore, superconducting detection systems with ultrahigh-sensitivity were developed, allowing the direct observation of the single trapped proton, as well as the high-precision determination of its eigenfrequencies. Based on novel experimental methods, which were developed in the framework of this thesis, the axial frequency of the particle was stabilized to a level, where the observation of single-proton spin-flips is possible, which was demonstrated. This experimental success is one of the most important steps towards the high-precision determination of the magnetic moment of the free proton. With the very first observation of spin transitions with a single trapped proton, a highly exciting perspective opens. All experimental techniques which were developed in this thesis can be directly applied to the antiproton. Thus, the first high-precision measurement of the magnetic moment of the antiproton becomes possible. This will provide a new high-precision test of the matterantimatter symmetry. (orig.)

Admittance spectroscopy or deep level transient spectroscopy: A contrasting juxtaposition

Science.gov (United States)

Bollmann, Joachim; Venter, Andre

2018-04-01

A comprehensive understanding of defects in semiconductors remains of primary importance. In this paper the effectiveness of two of the most commonly used semiconductor defect spectroscopy techniques, viz. deep level transient spectroscopy (DLTS) and admittance spectroscopy (AS) are reviewed. The analysis of defects present in commercially available SiC diodes shows that admittance spectroscopy allows the identification of deep traps with reduced measurement effort compared to deep Level Transient Spectroscopy (DLTS). Besides the N-donor, well-studied intrinsic defects were detected in these diodes. Determination of their activation energy and defect density, using the two techniques, confirm that the sensitivity of AS is comparable to that of DLTS while, due to its well defined peak shape, the spectroscopic resolution is superior. Additionally, admittance spectroscopy can analyze faster emission processes which make the study of shallow defects more practical and even that of shallow dopant levels, possible. A comparative summary for the relevant spectroscopic features of the two capacitance methods are presented.

A novel software assistant for the clinical analysis of MR spectroscopy with MeVisLab

Science.gov (United States)

Merkel, Bernd; Harz, Markus T.; Konrad, Olaf; Hahn, Horst K.; Peitgen, Heinz-Otto

2008-03-01

We present a novel software assistant for the analysis of multi-voxel 2D or 3D in-vivo-spectroscopy signals based on the rapid-prototyping platform MeVisLab. Magnetic Resonance Spectroscopy (MRS) is a valuable in-vivo metabolic window into tissue regions of interest, such as the brain, breast or prostate. With this method, the metabolic state can be investigated non-invasively. Different pathologies evoke characteristically different MRS signals, e.g., in prostate cancer, choline levels increase while citrate levels decrease compared to benign tissue. Concerning the majority of processing steps, available MRS tools lack performance in terms of speed. Our goal is to support clinicians in a fast and robust interpretation of MRS signals and to enable them to interactively work with large volumetric data sets. These data sets consist of 3D spatially resolved measurements of metabolite signals. The software assistant provides standard analysis methods for MRS data including data import and filtering, spatio-temporal Fourier transformation, and basic calculation of peak areas and spectroscopic metabolic maps. Visualization relies on the facilities of MeVisLab, a platform for developing clinically applicable software assistants. It is augmented by special-purpose viewing extensions and offers synchronized 1D, 2D, and 3D views of spectra and metabolic maps. A novelty in MRS processing tools is the side-by-side viewing ability of standard FT processed spectra with the results of time-domain frequency analysis algorithms like Linear Prediction and the Matrix Pencil Method. This enables research into the optimal toolset and workflow required to avoid misinterpretation and misapplication.

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.

Mathematical Descriptions of Axially Varying Penning Traps for the Antimatter Experiment: gravity, Interferometry, and Spectroscopy

CERN Document Server

Stephanie, Brown

2015-01-01

Antimatter, though proposed in 1933, is still not well understood. AEgIS aims to study the interaction of antihydrogen with the earth's gravitational field. This information will add to our understanding of the matter-antimatter asymmetry present in our universe. This paper discusses a Penning-Malmberg with a magnetic mirror that will hold $C_{2}^{-}$ that will be used for sympathetic cooling of antiprotons before the antihydrogen is created. The trap, which is critical to the cooling process of the antihydrogen, can be characterized by the separatrix between trapped and untrapped particles. This paper applies analytical processes used to define the separatrix of pure electron plasmas to a molecular plasma. Our work is based on the desire conditions (density, particle number, field strength, trap size) of the high field region. The initial application of a semi-analytical method applied to our trap defines the trap potential difference at \\~ 0.6V. The separatrix is defined in both the high and low fiel...

Analysis of carrier transport and carrier trapping in organic diodes with polyimide-6,13-Bis(triisopropylsilylethynyl)pentacene double-layer by charge modulation spectroscopy and optical second harmonic generation measurement

Energy Technology Data Exchange (ETDEWEB)

Lim, Eunju, E-mail: elim@dankook.ac.kr, E-mail: taguchi.d.aa@m.titech.ac.jp, E-mail: iwamoto@pe.titech.ac.jp [Department of Applied Physics, Institute of Nanosensor and Biotechnology, Dankook University, Jukjeon-dong, Gyeonggi-do 448-701 (Korea, Republic of); Taguchi, Dai, E-mail: elim@dankook.ac.kr, E-mail: taguchi.d.aa@m.titech.ac.jp, E-mail: iwamoto@pe.titech.ac.jp; Iwamoto, Mitsumasa, E-mail: elim@dankook.ac.kr, E-mail: taguchi.d.aa@m.titech.ac.jp, E-mail: iwamoto@pe.titech.ac.jp [Department of Physical Electronics, Tokyo Institute of Technology 2-12-1, O-okayama, Meguro-ku, Tokyo 152-8552 (Japan)

2014-08-18

We studied the carrier transport and carrier trapping in indium tin oxide/polyimide (PI)/6,13-Bis(triisopropylsilylethynyl)pentacene (TIPS-pentacene)/Au diodes by using charge modulation spectroscopy (CMS) and time-resolved electric field induced optical second harmonic generation (TR-EFISHG) measurements. TR-EFISHG directly probes the spatial carrier behaviors in the diodes, and CMS is useful in explaining the carrier motion with respect to energy. The results clearly indicate that the injected carriers move across TIPS-pentacene thorough the molecular energy states of TIPS-pentacene and accumulate at the PI/TIPS-pentacene interface. However, some carriers are trapped in the PI layers. These findings take into account the capacitance-voltage and current-voltage characteristics of the diodes.

A cylindrical quadrupole ion trap in combination with an electrospray ion source for gas-phase luminescence and absorption spectroscopy

International Nuclear Information System (INIS)

Stockett, Mark H.; Houmøller, Jørgen; Støchkel, Kristian; Svendsen, Annette; Brøndsted Nielsen, Steen

2016-01-01

A relatively simple setup for collection and detection of light emitted from isolated photo-excited molecular ions has been constructed. It benefits from a high collection efficiency of photons, which is accomplished by using a cylindrical ion trap where one end-cap electrode is a mesh grid combined with an aspheric condenser lens. The geometry permits nearly 10% of the emitted light to be collected and, after transmission losses, approximately 5% to be delivered to the entrance of a grating spectrometer equipped with a detector array. The high collection efficiency enables the use of pulsed tunable lasers with low repetition rates (e.g., 20 Hz) instead of continuous wave (cw) lasers or very high repetition rate (e.g., MHz) lasers that are typically used as light sources for gas-phase fluorescence experiments on molecular ions. A hole has been drilled in the cylinder electrode so that a light pulse can interact with the ion cloud in the center of the trap. Simulations indicate that these modifications to the trap do not significantly affect the storage capability and the overall shape of the ion cloud. The overlap between the ion cloud and the laser light is basically 100%, and experimentally >50% of negatively charged chromophore ions are routinely photodepleted. The performance of the setup is illustrated based on fluorescence spectra of several laser dyes, and the quality of these spectra is comparable to those reported by other groups. Finally, by replacing the optical system with a channeltron detector, we demonstrate that the setup can also be used for gas-phase action spectroscopy where either depletion or fragmentation is monitored to provide an indirect measurement on the absorption spectrum of the ion.

A cylindrical quadrupole ion trap in combination with an electrospray ion source for gas-phase luminescence and absorption spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Stockett, Mark H., E-mail: stockett@phys.au.dk; Houmøller, Jørgen; Støchkel, Kristian; Svendsen, Annette; Brøndsted Nielsen, Steen [Department of Physics and Astronomy, Aarhus University, Aarhus (Denmark)

2016-05-15

A relatively simple setup for collection and detection of light emitted from isolated photo-excited molecular ions has been constructed. It benefits from a high collection efficiency of photons, which is accomplished by using a cylindrical ion trap where one end-cap electrode is a mesh grid combined with an aspheric condenser lens. The geometry permits nearly 10% of the emitted light to be collected and, after transmission losses, approximately 5% to be delivered to the entrance of a grating spectrometer equipped with a detector array. The high collection efficiency enables the use of pulsed tunable lasers with low repetition rates (e.g., 20 Hz) instead of continuous wave (cw) lasers or very high repetition rate (e.g., MHz) lasers that are typically used as light sources for gas-phase fluorescence experiments on molecular ions. A hole has been drilled in the cylinder electrode so that a light pulse can interact with the ion cloud in the center of the trap. Simulations indicate that these modifications to the trap do not significantly affect the storage capability and the overall shape of the ion cloud. The overlap between the ion cloud and the laser light is basically 100%, and experimentally >50% of negatively charged chromophore ions are routinely photodepleted. The performance of the setup is illustrated based on fluorescence spectra of several laser dyes, and the quality of these spectra is comparable to those reported by other groups. Finally, by replacing the optical system with a channeltron detector, we demonstrate that the setup can also be used for gas-phase action spectroscopy where either depletion or fragmentation is monitored to provide an indirect measurement on the absorption spectrum of the ion.

Quantized motion of trapped ions

International Nuclear Information System (INIS)

Steinbach, J.

1999-01-01

This thesis is concerned with a theoretical and numerical study of the preparation and coherent manipulation of quantum states in the external and internal degrees of freedom of trapped ions. In its first part, this thesis proposes and investigates schemes for generating several nonclassical states for the quantized vibrational motion of a trapped ion. Based on dark state preparation specific laser excitation configurations are presented which, given appropriately chosen initial states, realize the desired motional states in the steady-state, indicated by the cessation of the fluorescence emitted by the ion. The focus is on the SU(1,1) intelligent states in both their single- and two-mode realization, corresponding to one- and two-dimensional motion of the ion. The presented schemes are also studied numerically using a Monte-Carlo state-vector method. The second part of the thesis describes how two vibrational degrees of freedom of a single trapped ion can be coupled through the action of suitably chosen laser excitation. Concentrating on a two-dimensional ion trap with dissimilar vibrational frequencies a variety of quantized two-mode couplings are derived. The focus is on a linear coupling that takes excitations from one mode to another. It is demonstrated how this can result in a state rotation, in which it is possible to coherently transfer the motional state of the ion between orthogonal directions without prior knowledge of that motional state. The third part of this thesis presents a new efficient method for generating maximally entangled internal states of a collection of trapped ions. The method is deterministic and independent of the number of ions in the trap. As the essential element of the scheme a mechanism for the realization of a controlled NOT operation that can operate on multiple ions is proposed. The potential application of the scheme for high-precision frequency standards is explored. (author)

Frequency locking of an extended-cavity quantum cascade laser to a frequency comb for precision mid infrared spectroscopy

KAUST Repository

Alsaif, Bidoor; Lamperti, Marco; Gatti, Davide; Laporta, Paolo; Fermann, Martin E.; Farooq, Aamir; Marangoni, Marco

2017-01-01

Extended-cavity quantum cascade lasers (EC-QCLs) enable mode-hope-free frequency sweeps in the mid-infrared region over ranges in excess of 100 cm−1, at speeds up to 1 THz/s and with a 100-mW optical power level. This makes them ideally suited for broadband absorption spectroscopy and for the simultaneous detection of multiple gases. On the other hand, their use for precision spectroscopy has been hampered so far by a large amount of frequency noise, resulting in an optical linewidth of about 30 MHz over 50 ms [1]. This is one of the reasons why neither their frequency nor their phase have been so far locked to a frequency comb. Their use in combination with frequency combs has been performed in an open loop regime only [2], which has the merit of preserving the inherently fast modulation speed of these lasers, yet not to afford high spectral resolution and accuracy.

Frequency locking of an extended-cavity quantum cascade laser to a frequency comb for precision mid infrared spectroscopy

KAUST Repository

Alsaif, Bidoor

2017-11-02

Extended-cavity quantum cascade lasers (EC-QCLs) enable mode-hope-free frequency sweeps in the mid-infrared region over ranges in excess of 100 cm−1, at speeds up to 1 THz/s and with a 100-mW optical power level. This makes them ideally suited for broadband absorption spectroscopy and for the simultaneous detection of multiple gases. On the other hand, their use for precision spectroscopy has been hampered so far by a large amount of frequency noise, resulting in an optical linewidth of about 30 MHz over 50 ms [1]. This is one of the reasons why neither their frequency nor their phase have been so far locked to a frequency comb. Their use in combination with frequency combs has been performed in an open loop regime only [2], which has the merit of preserving the inherently fast modulation speed of these lasers, yet not to afford high spectral resolution and accuracy.

Developments for the HITRAP cooler trap and mass measurements around A = 96 at SHIPTRAP

Energy Technology Data Exchange (ETDEWEB)

Koszudowski, Stephen

2009-07-08

The HITRAP (Highly charged Ions Trap) facility is currently being set up and commissioned at GSI in Darmstadt. It will provide bunches of 10{sup 5} heavy highly-charged ions, for example hydrogen-like uranium (U{sup 91+}), to high-precision atomic physics experiments. The ions are produced by the GSI accelerator complex and decelerated to 4 MeV/u in the Experimental Storage Ring. Then the ions are decelerated by a two-step linear decelerator down to 6 keV/u. The first deceleration step down to 500 keV/u was successfully commissioned. The decelerated ions are injected into a Penning trap (the Cooler Trap), where they are cooled to 4 K by electron and resistive cooling. Resonant circuits for non-destructive detection and the resistive cooling of the trapped particles were designed and tested. The time control of the trap-cycle (trapping, cooling, extraction) with a time resolution of 25 ns was implemented into the control system CS. CS is also used at the mass measurement Penning trap SHIPTRAP, where the new time control is successfully operated. SHIPTRAP measures radioactive ions stemming from fusion evaporation reactions at the velocity filter SHIP. The masses of 9 nuclides ({sup 93,94,95}Technetium, {sup 94,96}Ruthenium, {sup 95,96,97,98}Rhodium) near the line of stability were precisely measured and compared with the Atomic Mass Evaluation. The detection of isomeric states with the present SHIPTRAP set-up was studied. (orig.)

Developments for the HITRAP cooler trap and mass measurements around A = 96 at SHIPTRAP

International Nuclear Information System (INIS)

Koszudowski, Stephen

2009-01-01

The HITRAP (Highly charged Ions Trap) facility is currently being set up and commissioned at GSI in Darmstadt. It will provide bunches of 10 5 heavy highly-charged ions, for example hydrogen-like uranium (U 91+ ), to high-precision atomic physics experiments. The ions are produced by the GSI accelerator complex and decelerated to 4 MeV/u in the Experimental Storage Ring. Then the ions are decelerated by a two-step linear decelerator down to 6 keV/u. The first deceleration step down to 500 keV/u was successfully commissioned. The decelerated ions are injected into a Penning trap (the Cooler Trap), where they are cooled to 4 K by electron and resistive cooling. Resonant circuits for non-destructive detection and the resistive cooling of the trapped particles were designed and tested. The time control of the trap-cycle (trapping, cooling, extraction) with a time resolution of 25 ns was implemented into the control system CS. CS is also used at the mass measurement Penning trap SHIPTRAP, where the new time control is successfully operated. SHIPTRAP measures radioactive ions stemming from fusion evaporation reactions at the velocity filter SHIP. The masses of 9 nuclides ( 93,94,95 Technetium, 94,96 Ruthenium, 95,96,97,98 Rhodium) near the line of stability were precisely measured and compared with the Atomic Mass Evaluation. The detection of isomeric states with the present SHIPTRAP set-up was studied. (orig.)

Recent developments in trapping and manipulation of atoms with adiabatic potentials

Science.gov (United States)

Garraway, Barry M.; Perrin, Hélène

2016-09-01

A combination of static and oscillating magnetic fields can be used to ‘dress’ atoms with radio-frequency (RF), or microwave, radiation. The spatial variation of these fields can be used to create an enormous variety of traps for ultra-cold atoms and quantum gases. This article reviews the type and character of these adiabatic traps and the applications which include atom interferometry and the study of low-dimensional quantum systems. We introduce the main concepts of magnetic traps leading to adiabatic dressed traps. The concept of adiabaticity is discussed in the context of the Landau-Zener model. The first bubble trap experiment is reviewed together with the method used for loading it. Experiments based on atom chips show the production of double wells and ring traps. Dressed atom traps can be evaporatively cooled with an additional RF field, and a weak RF field can be used to probe the spectroscopy of the adiabatic potentials. Several approaches to ring traps formed from adiabatic potentials are discussed, including those based on atom chips, time-averaged adiabatic potentials and induction methods. Several proposals for adiabatic lattices with dressed atoms are also reviewed.

Evaluating potential sources of variation in Chironomidae catch rates on sticky traps

Science.gov (United States)

Smith, Joshua T.; Muehlbauer, Jeffrey D.; Kennedy, Theodore A.

2016-01-01

Sticky traps are a convenient tool for assessing adult aquatic insect population dynamics, but there are many practical questions about how trap sampling artefacts may affect observed results. Utilising study sites on the Colorado River and two smaller streams in northern Arizona, USA, we evaluated whether catch rates and sex ratios of Chironomidae, a ubiquitous aquatic insect, were affected by spraying traps with insecticide, placing traps at different heights above ground, and placing traps at different locations within a terrestrial habitat patch. We also evaluated temporal variation in Chironomidae counts monthly over a 9-month growing season. We found no significant variation in catch rates or sex ratios between traps treated versus untreated with insecticide, nor between traps placed at the upstream or downstream end of a terrestrial habitat patch. Traps placed near ground level did have significantly higher catch rates than traps placed at 1.5 m, although sex ratios were similar across heights. Chironomidae abundance and sex ratios also varied from month-to-month and seemed to be related to climatic conditions. Our results inform future sticky trap studies by demonstrating that trap height, but not insecticide treatment or precise trap placement within a habitat patch, is an important source of variation influencing catch rates.

Surface chemistry of plasma-assisted atomic layer deposition of Al2O3 studied by infrared spectroscopy

NARCIS (Netherlands)

Langereis, E.; Keijmel, J.; Sanden, van de M.C.M.; Kessels, W.M.M.

2008-01-01

The surface groups created during plasma-assisted atomic layer deposition (ALD) of Al2O3 were studied by infrared spectroscopy. For temperatures in the range of 25–150 °C, –CH3 and –OH were unveiled as dominant surface groups after the Al(CH3)3precursor and O2 plasma half-cycles, respectively. At

Penning-trap mass spectrometry of radioactive, highly charged ions. Measurements of neutron-rich Rb and Sr nuclides for nuclear astrophysics and development of a novel Penning trap for cooling highly charged ions

International Nuclear Information System (INIS)

Simon, Vanessa Veronique

2012-01-01

High-precision atomic mass measurements are vital for the description of nuclear structure, investigations of nuclear astrophysical processes, and tests of fundamental symmetries. The neutron-rich A ∼ 100 region presents challenges for modeling the astrophysical r-process because of sudden nuclear shape transitions. This thesis reports on high-precision masses of short-lived neutron-rich 94,97,98 Rb and 94,97-99 Sr isotopes using the TITAN Penning-trap mass spectrometer at TRIUMF. The isotopes were charge-bred to q = 15+; uncertainties of less than 4 keV were achieved. Results deviate by up to 11σ compared to earlier measurements and extend the region of nuclear deformation observed in the A∼100 region. A parameterized r-process model network calculation shows that mass uncertainties for the elemental abundances in this region are now negligible. Although beneficial for the measurement precision, the charge breeding process leads to an increased energy spread of the ions on the order of tens of eV/q. To eliminate this drawback, a Cooler Penning Trap (CPET) has been developed as part of this thesis. The novel multi-electrode trap structure of CPET forms nested potentials to cool HCI sympathetically using either electrons or protons to increase the overall efficiency and precision of the mass measurement. The status of the off-line setup and initial commissioning experiments are presented.

Fabrication of three-dimensional scaffolds using precision extrusion deposition with an assisted cooling device.

Science.gov (United States)

Hamid, Q; Snyder, J; Wang, C; Timmer, M; Hammer, J; Guceri, S; Sun, W

2011-09-01

In the field of biofabrication, tissue engineering and regenerative medicine, there are many methodologies to fabricate a building block (scaffold) which is unique to the target tissue or organ that facilitates cell growth, attachment, proliferation and/or differentiation. Currently, there are many techniques that fabricate three-dimensional scaffolds; however, there are advantages, limitations and specific tissue focuses of each fabrication technique. The focus of this initiative is to utilize an existing technique and expand the library of biomaterials which can be utilized to fabricate three-dimensional scaffolds rather than focusing on a new fabrication technique. An expanded library of biomaterials will enable the precision extrusion deposition (PED) device to construct three-dimensional scaffolds with enhanced biological, chemical and mechanical cues that will benefit tissue generation. Computer-aided motion and extrusion drive the PED to precisely fabricate micro-scaled scaffolds with biologically inspired, porosity, interconnectivity and internal and external architectures. The high printing resolution, precision and controllability of the PED allow for closer mimicry of tissues and organs. The PED expands its library of biopolymers by introducing an assisting cooling (AC) device which increases the working extrusion temperature from 120 to 250 °C. This paper investigates the PED with the integrated AC's capabilities to fabricate three-dimensional scaffolds that support cell growth, attachment and proliferation. Studies carried out in this paper utilized a biopolymer whose melting point is established to be 200 °C. This polymer was selected to illustrate the newly developed device's ability to fabricate three-dimensional scaffolds from a new library of biopolymers. Three-dimensional scaffolds fabricated with the integrated AC device should illustrate structural integrity and ability to support cell attachment and proliferation.

Fabrication of three-dimensional scaffolds using precision extrusion deposition with an assisted cooling device

International Nuclear Information System (INIS)

Hamid, Q; Snyder, J; Wang, C; Guceri, S; Sun, W; Timmer, M; Hammer, J

2011-01-01

In the field of biofabrication, tissue engineering and regenerative medicine, there are many methodologies to fabricate a building block (scaffold) which is unique to the target tissue or organ that facilitates cell growth, attachment, proliferation and/or differentiation. Currently, there are many techniques that fabricate three-dimensional scaffolds; however, there are advantages, limitations and specific tissue focuses of each fabrication technique. The focus of this initiative is to utilize an existing technique and expand the library of biomaterials which can be utilized to fabricate three-dimensional scaffolds rather than focusing on a new fabrication technique. An expanded library of biomaterials will enable the precision extrusion deposition (PED) device to construct three-dimensional scaffolds with enhanced biological, chemical and mechanical cues that will benefit tissue generation. Computer-aided motion and extrusion drive the PED to precisely fabricate micro-scaled scaffolds with biologically inspired, porosity, interconnectivity and internal and external architectures. The high printing resolution, precision and controllability of the PED allow for closer mimicry of tissues and organs. The PED expands its library of biopolymers by introducing an assisting cooling (AC) device which increases the working extrusion temperature from 120 to 250 deg. C. This paper investigates the PED with the integrated AC's capabilities to fabricate three-dimensional scaffolds that support cell growth, attachment and proliferation. Studies carried out in this paper utilized a biopolymer whose melting point is established to be 200 deg. C. This polymer was selected to illustrate the newly developed device's ability to fabricate three-dimensional scaffolds from a new library of biopolymers. Three-dimensional scaffolds fabricated with the integrated AC device should illustrate structural integrity and ability to support cell attachment and proliferation.

Action spectroscopy of SrCl{sup +} using an integrated ion trap time-of-flight mass spectrometer

Energy Technology Data Exchange (ETDEWEB)

Puri, Prateek, E-mail: teek24@ucla.edu; Schowalter, Steven J.; Hudson, Eric R. [Department of Physics and Astronomy, University of California, Los Angeles, California 90095 (United States); Kotochigova, Svetlana; Petrov, Alexander [Department of Physics, Temple University, Philadelphia, Pennsylvania 19122 (United States)

2014-07-07

The photodissociation cross-section of SrCl{sup +} is measured in the spectral range of 36 000–46 000 cm{sup −1} using a modular time-of-flight mass spectrometer (TOF-MS). By irradiating a sample of trapped SrCl{sup +} molecular ions with a pulsed dye laser, X{sup 1}Σ{sup +} state molecular ions are electronically excited to the repulsive wall of the A{sup 1}Π state, resulting in dissociation. Using the TOF-MS, the product fragments are detected and the photodissociation cross-section is determined for a broad range of photon energies. Detailed ab initio calculations of the SrCl{sup +} molecular potentials and spectroscopic constants are also performed and are found to be in good agreement with experiment. The spectroscopic constants for SrCl{sup +} are also compared to those of another alkaline earth halogen, BaCl{sup +}, in order to highlight structural differences between the two molecular ions. This work represents the first spectroscopy and ab initio calculations of SrCl{sup +}.

Effect of the interaction among traps on the shape of thermoluminescence glow curves

International Nuclear Information System (INIS)

Marcazzo, J.; Santiago, M.; Spano, F.; Lester, M.; Ortega, F.; Molina, P.; Caselli, E.

2007-01-01

The effect of the interaction among traps on the structure of thermoluminescence glow curves has been investigated by generating numerically simulated glow curves for a wide range of trap parameters. The results reported in this paper provide useful insights which assist in the analysis of experimental glow curves. The most important result shows that it is incorrect to assume beforehand that each peak is related to a specific trapping state. The validity of the quasiequilibrium approximation is briefly discussed

Robotic-Arm Assisted Total Knee Arthroplasty Demonstrated Greater Accuracy and Precision to Plan Compared with Manual Techniques.

Science.gov (United States)

Hampp, Emily L; Chughtai, Morad; Scholl, Laura Y; Sodhi, Nipun; Bhowmik-Stoker, Manoshi; Jacofsky, David J; Mont, Michael A

2018-05-01

This study determined if robotic-arm assisted total knee arthroplasty (RATKA) allows for more accurate and precise bone cuts and component position to plan compared with manual total knee arthroplasty (MTKA). Specifically, we assessed the following: (1) final bone cuts, (2) final component position, and (3) a potential learning curve for RATKA. On six cadaver specimens (12 knees), a MTKA and RATKA were performed on the left and right knees, respectively. Bone-cut and final-component positioning errors relative to preoperative plans were compared. Median errors and standard deviations (SDs) in the sagittal, coronal, and axial planes were compared. Median values of the absolute deviation from plan defined the accuracy to plan. SDs described the precision to plan. RATKA bone cuts were as or more accurate to plan based on nominal median values in 11 out of 12 measurements. RATKA bone cuts were more precise to plan in 8 out of 12 measurements ( p  ≤ 0.05). RATKA final component positions were as or more accurate to plan based on median values in five out of five measurements. RATKA final component positions were more precise to plan in four out of five measurements ( p  ≤ 0.05). Stacked error results from all cuts and implant positions for each specimen in procedural order showed that RATKA error was less than MTKA error. Although this study analyzed a small number of cadaver specimens, there were clear differences that separated these two groups. When compared with MTKA, RATKA demonstrated more accurate and precise bone cuts and implant positioning to plan. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Radiation trapping in atomic absorption spectroscopy at lead determination in different matricies

International Nuclear Information System (INIS)

El-Gohary, Z.

2005-01-01

The determination of lead by flame atomic absorption analysis in the presence of Sn and Fe atoms and different matrices such as OH and SO 3 was investigated with the objective of understanding the spectral interference processes at the analytical lines 283.31 nm for a wide range of concentration. The radiation trapping factor was interpreted and evaluated assuming Voigt distribution of the atomic and rotational lines in the flame. The radiation trapping factor was increased by increasing the number density (plasma of the absorbing medium is optically thick). In plasma, there is a certain point of equilibrium between the trapping and the escaping of radiation, which is relevant to 50% of absorption. The spectral background interference can cause a variation of the number density at equilibrium point as a result of the degree of overlap with the analytical line. The spectral background interference can be easily avoided by using another resonance absorption line for the analysis. The chemical modification of the matrix is applied to minimize the interference effect. Nitric acid, ammonium nitrate and magnesium nitrate are most commonly recommended as matrix modifiers

New software tools for enhanced precision in robot-assisted laser phonomicrosurgery.

Science.gov (United States)

Dagnino, Giulio; Mattos, Leonardo S; Caldwell, Darwin G

2012-01-01

This paper describes a new software package created to enhance precision during robot-assisted laser phonomicrosurgery procedures. The new software is composed of three tools for camera calibration, automatic tumor segmentation, and laser tracking. These were designed and developed to improve the outcome of this demanding microsurgical technique, and were tested herein to produce quantitative performance data. The experimental setup was based on the motorized laser micromanipulator created by Istituto Italiano di Tecnologia and the experimental protocols followed are fully described in this paper. The results show the new tools are robust and effective: The camera calibration tool reduced residual errors (RMSE) to 0.009 ± 0.002 mm under 40× microscope magnification; the automatic tumor segmentation tool resulted in deep lesion segmentations comparable to manual segmentations (RMSE= 0.160 ± 0.028 mm under 40× magnification); and the laser tracker tool proved to be reliable even during cutting procedures (RMSE= 0.073 ± 0.023 mm under 40× magnification). These results demonstrate the new software package can provide excellent improvements to the previous microsurgical system, leading to important enhancements in surgical outcome.

All-optical atom trap as a target for MOTRIMS-like collision experiments

Science.gov (United States)

Sharma, S.; Acharya, B. P.; De Silva, A. H. N. C.; Parris, N. W.; Ramsey, B. J.; Romans, K. L.; Dorn, A.; de Jesus, V. L. B.; Fischer, D.

2018-04-01

Momentum-resolved scattering experiments with laser-cooled atomic targets have been performed since almost two decades with magneto-optical trap recoil ion momentum spectroscopy (MOTRIMS) setups. Compared to experiments with gas-jet targets, MOTRIMS features significantly lower target temperatures allowing for an excellent recoil ion momentum resolution. However, the coincident and momentum-resolved detection of electrons was long rendered impossible due to incompatible magnetic field requirements. Here we report on an experimental approach which is based on an all-optical 6Li atom trap that—in contrast to magneto-optical traps—does not require magnetic field gradients in the trapping region. Atom temperatures of about 2 mK and number densities up to 109 cm-3 make this trap ideally suited for momentum-resolved electron-ion coincidence experiments. The overall configuration of the trap is very similar to conventional magneto-optical traps. It mainly requires small modifications of laser beam geometries and polarization which makes it easily implementable in other existing MOTRIMS experiments.

Trapped electron decay by the thermally-assisted tunnelling to electron acceptors in glassy matrices. A computer simulation study

International Nuclear Information System (INIS)

Feret, B.; Bartczak, W.M.; Kroh, J.

1991-01-01

The Redi-Hopefield quantum mechanical model of the thermally-assisted electron transfer has been applied to simulate the decay of trapped electrons by tunnelling to electron acceptor molecules added to the glassy matrix. It was assumed that the electron energy levels in donors and acceptors are statistically distributed and the electron excess energy after transfer is dissipated in the medium by the electron-phonon coupling. The electron decay curves were obtained by the method of computer simulation. It was found that for a given medium there exists a certain preferred value of the electronic excess energy which can be effectively converted into the matrix vibrations. If the mismatch of the electron states on the donor and acceptor coincides with the ''resonance'' energy the overall kinetics of electron transfer is accelerated. (author)

Charge trapping/de-trapping in nitrided SiO2 dielectrics and its influence on device reliability

Science.gov (United States)

Kambour, Kenneth; Hjalmarson, Harold; Nguyen, Duc; Kouhestani, Camron; Devine, Roderick

2012-02-01

Field effect devices with insulator gate dielectrics are excellent test vehicles to probe the physics of defects and charge trapping in the insulator/ semiconductor structure. p-channel field effect device reliability under negative bias stressing has been identified to originate from at least two terms: a) charged defect generation at the Si substrate/SiOxNy interface and b) charge trapping at neutral defect pre-cursors in the ``bulk'' of the SiOxNy beyond the interface. Measurements of transistor characteristics enable extraction of the two terms. We report the results of such measurements and demonstrate that short time effects are associated primarily with electric field assisted tunneling of holes from the inversion layer to neutral traps. This is confirmed by bias stressing measurements at different frequencies in the range 1 Hz to 2 MHz. First principles modeling of the tunneling/trapping phenomena is presented. K.Kambour worked under contract FA9453-08-C-0245 with the Air Force Research Laboratory/RVSE. Sandia National Labs is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Conduction mechanism of leakage current due to the traps in ZrO2 thin film

International Nuclear Information System (INIS)

Seo, Yohan; Lee, Sangyouk; An, Ilsin; Jeong, Heejun; Song, Chulgi

2009-01-01

In this work, a metal-oxide-semiconductor capacitor with zirconium oxide (ZrO 2 ) gate dielectric was fabricated by an atomic layer deposition (ALD) technique and the leakage current characteristics under negative bias were studied. From the result of current–voltage curves there are two possible conduction mechanisms to explain the leakage current in the ZrO 2 thin film. The dominant mechanism is the space charge limited conduction in the high-electric field region (1.5–5.0 MV cm −1 ) while the trap-assisted tunneling due to the existence of traps is prevailed in the low-electric field region (0.8–1.5 MV cm −1 ). Conduction caused by the trap-assisted tunneling is found from the experimental results of a weak temperature dependence of current, and the trap barrier height is obtained. The space charge limited conduction is evidenced, for different temperatures, by Child's law dependence of current density versus voltage. Child's law dependence can be explained by considering a single discrete trapping level and we can obtain the activation energy of 0.22 eV

Conduction mechanism of leakage current due to the traps in ZrO2 thin film

Science.gov (United States)

Seo, Yohan; Lee, Sangyouk; An, Ilsin; Song, Chulgi; Jeong, Heejun

2009-11-01

In this work, a metal-oxide-semiconductor capacitor with zirconium oxide (ZrO2) gate dielectric was fabricated by an atomic layer deposition (ALD) technique and the leakage current characteristics under negative bias were studied. From the result of current-voltage curves there are two possible conduction mechanisms to explain the leakage current in the ZrO2 thin film. The dominant mechanism is the space charge limited conduction in the high-electric field region (1.5-5.0 MV cm-1) while the trap-assisted tunneling due to the existence of traps is prevailed in the low-electric field region (0.8-1.5 MV cm-1). Conduction caused by the trap-assisted tunneling is found from the experimental results of a weak temperature dependence of current, and the trap barrier height is obtained. The space charge limited conduction is evidenced, for different temperatures, by Child's law dependence of current density versus voltage. Child's law dependence can be explained by considering a single discrete trapping level and we can obtain the activation energy of 0.22 eV.

Investigation of SAGD steam trap control in two and three dimensions

Energy Technology Data Exchange (ETDEWEB)

Edmunds, N. R. [Clearwater Engineering, AB (Canada)

1998-12-31

Steam trap production control has been traditionally recommended for steam-assisted gravity drainage (SAGD) operations. This study examines the relationship between producing steam trap subcool settings and related parameters of interest such as fluid level, pressure, production rate, and profitability for a prototype Athabasca reservoir. Study results indicate that the steam trap dynamics are far more complex than hitherto imagined, that 3-D simulations predict significantly lower production rates than 2-D simulations, and that these variations have implications for all aspects of SAGD engineering, including process optimization, production operations and performance analysis. 10 refs., 2 tabs., 15 figs.

Trap spectrum of the ``new oxygen donor'' in silicon

Science.gov (United States)

Hölzlein, K.; Pensl, G.; Schulz, M.

1984-07-01

Electronic properties of the new oxygen donor generated in phosphorus-doped Czochralski-silicon at 650‡C are investigated by deep level transient spectroscopy. A continuous distribution of trap states (1014 1016 cm-3 eV-1) is detected in the upper half of the band gap with increasing values towards the conduction band. The magnitude of the state density observed increases with the oxygen content, the heat duration, and a preanneal at temperatures lower than 650‡C. The continuous trap spectrum of the new donor is explained by interface states occuring at the surface of SiO x precipitates.

Trapping behaviour of deuterium ions implanted into tungsten simultaneously with carbon ions

International Nuclear Information System (INIS)

Kobayashi, Makoto; Suzuki, Sachiko; Wang, Wanjing; Kurata, Rie; Kida, Katsuya; Oya, Yasuhisa; Okuno, Kenji; Ashikawa, Naoko; Sagara, Akio; Yoshida, Naoaki

2009-01-01

The trapping behaviour of deuterium ions implanted into tungsten simultaneously with carbon ions was investigated by thermal desorption spectroscopy (TDS) and x-ray photoelectron spectroscopy (XPS). The D 2 TDS spectrum consisted of three desorption stages, namely desorption of deuterium trapped by intrinsic defects, ion-induced defects and carbon with the formation of the C-D bond. Although the deuterium retention trapped by intrinsic defects was almost constant, that by ion-induced defects increased as the ion fluence increased. The retention of deuterium with the formation of the C-D bond was saturated at an ion fluence of 0.5x10 22 D + m -2 , where the major process was changed from the sputtering of tungsten with the formation of a W-C mixture to the formation of a C-C layer, and deuterium retention as the C-D bond decreased. It was concluded that the C-C layer would enhance the chemical sputtering of carbon with deuterium with the formation of CD x and the chemical state of carbon would control the deuterium retention in tungsten under C + -D 2 + implantation.

WITCH, a Penning trap for weak interaction studies

CERN Document Server

Kozlov, V Yu

2005-01-01

This work is the completion of the installation of the WITCH set-up and the first tests and commissioning of it. The first goal of the WITCH experiment is to improve the present limit on a scalar interaction in nuclear $\\beta$-decay by determining the $\\beta$-neutrino angular correlation parameter $a$ via a precise measurement of the shape of the energy spectrum of the recoil ions. The development of the WITCH set-up and its installation at ISOLDE (CERN) were recently completed. The principle of WITCH is based on a combination of a Penning trap to confine the radioactive ions and a retardation spectrometer to probe the energy of the recoil ions resulting from $\\beta$-decays in the trap. Extensive computer simulations show that for a reasonable measurement time a precision on the $a$-parameter of 0.5% can be achieved. This corresponds to an upper limit for the scalar interaction constant Cs/Cv < 9% at 95% C.L. Designing and constructing a set-up as large and complex as the WITCH set-up takes time, several y...

Fast Ground State Manipulation of Neutral Atoms in Microscopic Optical Traps

International Nuclear Information System (INIS)

Yavuz, D.D.; Kulatunga, P.B.; Urban, E.; Johnson, T.A.; Proite, N.; Henage, T.; Walker, T.G.; Saffman, M.

2006-01-01

We demonstrate Rabi flopping at MHz rates between ground hyperfine states of neutral 87 Rb atoms that are trapped in two micron sized optical traps. Using tightly focused laser beams we demonstrate high fidelity, site specific Rabi rotations with cross talk on neighboring sites separated by 8 μm at the level of 10 -3 . Ramsey spectroscopy is used to measure a dephasing time of 870 μs, which is ≅5000 times longer than the time for a π/2 pulse

Construction of a high resolution microscope with conventional and holographic optical trapping capabilities.

Science.gov (United States)

Butterfield, Jacqualine; Hong, Weili; Mershon, Leslie; Vershinin, Michael

2013-04-22

High resolution microscope systems with optical traps allow for precise manipulation of various refractive objects, such as dielectric beads (1) or cellular organelles (2,3), as well as for high spatial and temporal resolution readout of their position relative to the center of the trap. The system described herein has one such "traditional" trap operating at 980 nm. It additionally provides a second optical trapping system that uses a commercially available holographic package to simultaneously create and manipulate complex trapping patterns in the field of view of the microscope (4,5) at a wavelength of 1,064 nm. The combination of the two systems allows for the manipulation of multiple refractive objects at the same time while simultaneously conducting high speed and high resolution measurements of motion and force production at nanometer and piconewton scale.

Interfacial charge trapping in the polymer solar cells and its elimination by solvent annealing

Directory of Open Access Journals (Sweden)

A. K. Chauhan

2016-09-01

Full Text Available The PCDTBT:PCBM solar cells were fabricated adopting a tandem layer approach to investigate the critical issues of charge trapping, radiation absorption, and efficiency in polymer solar cells. This layered structure was found to be a source of charge trapping which was identified and confirmed by impedance spectroscopy. The low efficiency in multilayered structures was related to trapping of photo-generated carriers and low carrier mobility, and thus an increased recombination. Solvent annealing of the structures in tetrahydrofuran vapors was found beneficial in homogenizing the active layer, dissolving additional interfaces, and elimination of charge traps which improved the carrier mobilities and eventually the device efficiencies.

Chemical characterization of microparticles by laser ablation in an ion trap mass spectrometer

International Nuclear Information System (INIS)

Dale, J.M.; Whitten, W.B.; Ramsey, J.M.

1991-01-01

We are developing a new technique for the chemical characterization of microparticles based upon the use of electrodynamic traps. The electrodynamic trap has achieved widespread use in the mass spectrometry community in the form of the ion trap mass spectrometer or quadrupole ion trap. Small macroscopic particles can be confined or levitated within the electrode structure of a three-dimensional quadrupole electrodynamic trap in the same way as fundamental charges or molecular ions by using a combination of ac and dc potentials. Our concept is to use the same electrode structure to perform both microparticle levitation and ion trapping/mass analysis. The microparticle will first be trapped and spatially stabilized within the trap for characterization by optical probes, i.e., absorption, fluorescence, or Raman spectroscopy. After the particle has been optically characterized, it is further characterized using mass spectrometry. Ions are generated from the particle surface using laser ablation or desorption. The characteristics of the applied voltages are changed to trap the ions formed by the laser with the ions subsequently mass analyzed. The work described in this paper focuses on the ability to perform laser desorption experiments on microparticles contained within the ion trap

Atomic physics of highly charged ions in an electron beam ion trap

International Nuclear Information System (INIS)

Marrs, R.E.

1990-07-01

Two electron beam ion traps are in use at LLNL for the purpose of studying the properties of very highly charged ions and their interactions with electrons. This paper reviews the operation of the traps and discusses recent experiments in three areas: precision transition energy measurements in the limit of very high ion charge, dielectronic recombination measurements for the He-like isoelectronic sequence, and measurements of x-ray polarization. 22 refs., 11 figs., 1 tab

Femtosecond study of self-trapped vibrational excitons in crystalline acetanilide

DEFF Research Database (Denmark)

Edler, J.; Hamm, Peter; Scott, Alwyn C.

2002-01-01

Femtosecond IR spectroscopy of delocalized NH excitations of crystalline acetanilide confirms that self-trapping in hydrogen-bonded peptide units exists and does stabilize the excitation. Two phonons with frequencies of 48 and 76 cm(-1) are identified as the major degrees of freedom that mediate...

Fabrication of three-dimensional scaffolds using precision extrusion deposition with an assisted cooling device

Energy Technology Data Exchange (ETDEWEB)

Hamid, Q; Snyder, J; Wang, C; Guceri, S; Sun, W [Department of Mechanical Engineering and Mechanics, Drexel University, Philadelphia, PA (United States); Timmer, M; Hammer, J, E-mail: sunwei@drexel.edu [Advanced Technologies and Regenerative Medicine, Somerville, NJ (United States)

2011-09-15

In the field of biofabrication, tissue engineering and regenerative medicine, there are many methodologies to fabricate a building block (scaffold) which is unique to the target tissue or organ that facilitates cell growth, attachment, proliferation and/or differentiation. Currently, there are many techniques that fabricate three-dimensional scaffolds; however, there are advantages, limitations and specific tissue focuses of each fabrication technique. The focus of this initiative is to utilize an existing technique and expand the library of biomaterials which can be utilized to fabricate three-dimensional scaffolds rather than focusing on a new fabrication technique. An expanded library of biomaterials will enable the precision extrusion deposition (PED) device to construct three-dimensional scaffolds with enhanced biological, chemical and mechanical cues that will benefit tissue generation. Computer-aided motion and extrusion drive the PED to precisely fabricate micro-scaled scaffolds with biologically inspired, porosity, interconnectivity and internal and external architectures. The high printing resolution, precision and controllability of the PED allow for closer mimicry of tissues and organs. The PED expands its library of biopolymers by introducing an assisting cooling (AC) device which increases the working extrusion temperature from 120 to 250 deg. C. This paper investigates the PED with the integrated AC's capabilities to fabricate three-dimensional scaffolds that support cell growth, attachment and proliferation. Studies carried out in this paper utilized a biopolymer whose melting point is established to be 200 deg. C. This polymer was selected to illustrate the newly developed device's ability to fabricate three-dimensional scaffolds from a new library of biopolymers. Three-dimensional scaffolds fabricated with the integrated AC device should illustrate structural integrity and ability to support cell attachment and proliferation.

Laser Spectroscopy and Frequency Combs

International Nuclear Information System (INIS)

Hänsch, Theodor W; Picqué, Nathalie

2013-01-01

The spectrum of a frequency comb, commonly generated by a mode-locked femtosecond laser consists of several hundred thousand precisely evenly spaced spectral lines. Such laser frequency combs have revolutionized the art measuring the frequency of light, and they provide the long-missing clockwork for optical atomic clocks. The invention of the frequency comb technique has been motivated by precision laser spectroscopy of the simple hydrogen atom. The availability of commercial instruments is facilitating the evolution of new applications far beyond the original purpose. Laser combs are becoming powerful instruments for broadband molecular spectroscopy by dramatically improving the resolution and recording speed of Fourier spectrometers and by creating new opportunities for highly multiplexed nonlinear spectroscopy, such as two-photon spectroscopy or coherent Raman spectroscopy. Other emerging applications of frequency combs range from fundamental research in astronomy, chemistry, or attosecond science to telecommunications and satellite navigation

The trap states in lightly Mg-doped GaN grown by MOVPE on a freestanding GaN substrate

Science.gov (United States)

Narita, Tetsuo; Tokuda, Yutaka; Kogiso, Tatsuya; Tomita, Kazuyoshi; Kachi, Tetsu

2018-04-01

We investigated traps in lightly Mg-doped (2 × 1017 cm-3) p-GaN fabricated by metalorganic vapor phase epitaxy (MOVPE) on a freestanding GaN substrate and the subsequent post-growth annealing, using deep level transient spectroscopy. We identified four hole traps with energy levels of EV + 0.46, 0.88, 1.0, and 1.3 eV and one electron trap at EC - 0.57 eV in a p-type GaN layer uniformly doped with magnesium (Mg). The Arrhenius plot of hole traps with the highest concentration (˜3 × 1016 cm-3) located at EV + 0.88 eV corresponded to those of hole traps ascribed to carbon on nitrogen sites in n-type GaN samples grown by MOVPE. In fact, the range of the hole trap concentrations at EV + 0.88 eV was close to the carbon concentration detected by secondary ion mass spectroscopy. Moreover, the electron trap at EC - 0.57 eV was also identical to the dominant electron traps commonly observed in n-type GaN. Together, these results suggest that the trap states in the lightly Mg-doped GaN grown by MOVPE show a strong similarity to those in n-type GaN, which can be explained by the Fermi level close to the conduction band minimum in pristine MOVPE grown samples due to existing residual donors and Mg-hydrogen complexes.

A passion for precision

CERN Multimedia

CERN. Geneva. Audiovisual Unit

2006-01-01

For more than three decades, the quest for ever higher precision in laser spectroscopy of the simple hydrogen atom has inspired many advances in laser, optical, and spectroscopic techniques, culminating in femtosecond laser optical frequency combs as perhaps the most precise measuring tools known to man. Applications range from optical atomic clocks and tests of QED and relativity to searches for time variations of fundamental constants. Recent experiments are extending frequency comb techniques into the extreme ultraviolet. Laser frequency combs can also control the electric field of ultrashort light pulses, creating powerful new tools for the emerging field of attosecond science.

ESR study on free radicals trapped in crosslinked polytetrafluoroethylene (PTFE)

International Nuclear Information System (INIS)

Oshima, Akihiro; Tabata, Yoneho; Seguchi, Tadao

1997-01-01

Free radicals in crosslinked PTFE which formed by 60 Co γ-rays irradiation at 77 K and at room temperature were studied by electron spin resonance (ESR) spectroscopy. The crosslinked PTFE specimens with different crosslinking density were prepared by electron beam irradiation in the molten state. The ESR spectra observed in the irradiated crosslinked PTFE are much different from those in non-crosslinked PTFE (virgin); a broad singlet component increases with increasing the crosslinking density, G-value of radicals is much higher in crosslinked PTFE than in non-crosslinked one. Free radicals related to the broad component are trapped in the non-crystalline region of crosslinked PTFE and rather stable at room temperature, whereas radicals trapped in amorphous non-crosslinked PTFE are unstable at room temperature. It is thought that most of free radicals trapped in the crosslinked PTFE are formed in the crosslinked amorphous region. The trapped radicals decays around 383 K (110 o C) due to the molecular motion of α-relaxation. (Author)

Trap assisted charge multiplication enhanced photoresponse of Li-P codoped p-ZnO/n-Si heterojunction ultraviolet photodetectors

Science.gov (United States)

Sharma, Pankaj; Bhardwaj, Ritesh; Kumar, Amitesh; Mukherjee, Shaibal

2018-01-01

In this work, we report a high-performance p-ZnO/n-Si heterojunction-based ultraviolet (UV) photodetector fabricated by dual ion beam sputter deposition. The lithium-phosphorus (Li-P) codoping route was used to realize low resistive and stable p-type ZnO. The current-voltage characteristics of p-ZnO/n-Si heterojunction photodiode showed good rectifying behavior with a rectification ratio of 170 at  ±3 V. The spectral response measurements of the photodiode showed excellent responsivity with a peak observed around ~325 nm and cutoff wavelength around 370 nm. The maximum responsivity achieved was 2.6 A W-1 at an applied reverse bias of  -6 V. The external quantum efficiency determined was of the order of ~1000% which is attributed to the trap assisted multiplication of charge carriers.

Trapping guidelines for area-wide fruit fly programmes

International Nuclear Information System (INIS)

2003-11-01

Different traps and lures have been developed and used over decades to survey fruit fly populations. The first attractant for male fruit flies was methyl eugenol (ME) (for Bactrocera zonata, Howlett, 1912) followed by kerosene for Mediterranean fruit fly, Ceratitis capitata, (medfly), Severin and Severin, 1913. In 1956, Angelica seed oil was used to trap medfly (Steiner et al, 1957). Beroza et al. (1961) discovered trimedlure (TML) to be effective for the same purpose. Beroza and Green, 1963, demonstrated cuelure to be an effective attractant for Bactrocera cucurbitae. Food baits based on protein solutions, fermenting sugar solutions, fruit juices, and vinegar have been used since 1918 for the capture of females of several species. The McPhail trap was the first device to be used with protein baits (McPhail, 1929). Steiner traps were developed in 1957 (Steiner et al., 1957) and Jackson traps in 1971 for TML (Harris et al., 1971). These traps are currently used in various countries for fruit fly surveys in support of control activities and eradication campaigns. The combination of a McPhail trap with a protein attractant, Jackson trap with TML, and the Steiner trap with ME or cuelure (CUE), has remained unchanged for several decades. Global trends in increasing food quality, revenue sources, and fruit and vegetable trade, has resulted in an increased worldwide movement of fruit fly species and requires refinement of survey systems. After years of validating trapping technology through coordinated research programmes (CRP's) and extensive technical assistance to member countries, the Joint Division FAO/IAEA proposes the use of proven technologies in improving trap sensitivity in area-wide fruit fly control programmes (IAEA 1996 and IAEA 1998). These proven technologies include the use of synthetic food lures such as female attractants that can be used for several species of Anastrepha, Bactrocera and Ceratitis. Other citations of information on these developments are

Trapping guidelines for area-wide fruit fly programmes

Energy Technology Data Exchange (ETDEWEB)

NONE

2003-11-01

Different traps and lures have been developed and used over decades to survey fruit fly populations. The first attractant for male fruit flies was methyl eugenol (ME) (for Bactrocera zonata, Howlett, 1912) followed by kerosene for Mediterranean fruit fly, Ceratitis capitata, (medfly), Severin and Severin, 1913. In 1956, Angelica seed oil was used to trap medfly (Steiner et al, 1957). Beroza et al. (1961) discovered trimedlure (TML) to be effective for the same purpose. Beroza and Green, 1963, demonstrated cuelure to be an effective attractant for Bactrocera cucurbitae. Food baits based on protein solutions, fermenting sugar solutions, fruit juices, and vinegar have been used since 1918 for the capture of females of several species. The McPhail trap was the first device to be used with protein baits (McPhail, 1929). Steiner traps were developed in 1957 (Steiner et al., 1957) and Jackson traps in 1971 for TML (Harris et al., 1971). These traps are currently used in various countries for fruit fly surveys in support of control activities and eradication campaigns. The combination of a McPhail trap with a protein attractant, Jackson trap with TML, and the Steiner trap with ME or cuelure (CUE), has remained unchanged for several decades. Global trends in increasing food quality, revenue sources, and fruit and vegetable trade, has resulted in an increased worldwide movement of fruit fly species and requires refinement of survey systems. After years of validating trapping technology through coordinated research programmes (CRP's) and extensive technical assistance to member countries, the Joint Division FAO/IAEA proposes the use of proven technologies in improving trap sensitivity in area-wide fruit fly control programmes (IAEA 1996 and IAEA 1998). These proven technologies include the use of synthetic food lures such as female attractants that can be used for several species of Anastrepha, Bactrocera and Ceratitis. Other citations of information on these developments are

Photo-reactive charge trapping memory based on lanthanide complex

Science.gov (United States)

Zhuang, Jiaqing; Lo, Wai-Sum; Zhou, Li; Sun, Qi-Jun; Chan, Chi-Fai; Zhou, Ye; Han, Su-Ting; Yan, Yan; Wong, Wing-Tak; Wong, Ka-Leung; Roy, V. A. L.

2015-10-01

Traditional utilization of photo-induced excitons is popularly but restricted in the fields of photovoltaic devices as well as photodetectors, and efforts on broadening its function have always been attempted. However, rare reports are available on organic field effect transistor (OFET) memory employing photo-induced charges. Here, we demonstrate an OFET memory containing a novel organic lanthanide complex Eu(tta)3ppta (Eu(tta)3 = Europium(III) thenoyltrifluoroacetonate, ppta = 2-phenyl-4,6-bis(pyrazol-1-yl)-1,3,5-triazine), in which the photo-induced charges can be successfully trapped and detrapped. The luminescent complex emits intense red emission upon ultraviolet (UV) light excitation and serves as a trapping element of holes injected from the pentacene semiconductor layer. Memory window can be significantly enlarged by light-assisted programming and erasing procedures, during which the photo-induced excitons in the semiconductor layer are separated by voltage bias. The enhancement of memory window is attributed to the increasing number of photo-induced excitons by the UV light. The charges are stored in this luminescent complex for at least 104 s after withdrawing voltage bias. The present study on photo-assisted novel memory may motivate the research on a new type of light tunable charge trapping photo-reactive memory devices.

Trap assisted space charge conduction in p-NiO/n-ZnO heterojunction diode

International Nuclear Information System (INIS)

Tyagi, Manisha; Tomar, Monika; Gupta, Vinay

2015-01-01

Highlights: • p-NiO/n-ZnO heterojunction diode with enhanced junction parameters has been prepared. • Temperature dependent I–V throw insight into the involved conduction mechanism. • SCLC with exponential trap distribution was found to be the dominant mechanism. • C–V measurement at different frequencies support the presence of traps. - Abstract: The development of short-wavelength p–n junction is essentially important for the realization of transparent electronics for next-generation optoelectronic devices. In the present work, a p–n heterojunction diode based on p-NiO/n-ZnO has been prepared under the optimised growth conditions exhibiting improved electrical and junction parameters. The fabricated heterojunction gives typical current–voltage (I–V) characteristics with good rectifying behaviour (rectification ratio ≈ 10 4 at 2 V). The temperature dependent current–voltage characteristics of heterojunction diode have been studied and origin of conduction mechanism is identified. The space-charge limited conduction with exponential trap distribution having deep level trap is found to be the dominant conduction mechanism in the fabricated p–n heterojunction diode. The conduction and valence band discontinuities for NiO/ZnO heterostructure have been determined from the capacitance–voltage (C–V) measurements

PC operated acoustic transient spectroscopy of deep levels in MIS structures

International Nuclear Information System (INIS)

Bury, P.; Jamnicky, I.

1996-01-01

A new version of acoustic deep-level transient spectroscopy is presented to study the traps at the insulator-semiconductor interface. The acoustic deep-level transient spectroscopy uses an acoustoelectric response signal produced by the MIS structure interface when a longitudinal acoustic wave propagates through a structure. The acoustoelectric response signal is extremely sensitive to external conditions of the structure and reflects any changes in the charge distribution, connected also with charged traps. In comparison with previous version of acoustic deep-level transient spectroscopy that closely coincides with the principle of the original deep-level transient spectroscopy technique, the present technique is based on the computer-evaluated isothermal transients and represents an improved, more efficient and time saving technique. Many tests on the software used for calculation as well as on experimental setup have been performed. The improved acoustic deep-level transient spectroscopy method has been applied for the Si(p) MIS structures. The deep-level parameters as activation energy and capture cross-section have been determined. (authors)

Photoshop® Assisted Spectroscopy: An Economical and Non-Destructive Method for Tracking Color Shift.

Science.gov (United States)

Wright, Kristi; Herro, Holly

Many historically and culturally significant objects from the mid-to-late 20 th century were created with media which contains light sensitive dyes that present problems for collection custodians and conservators. The conservation staff at the National Library of Medicine (NLM), National Institutes of Health, conducted a multi-phase project on the aging of ballpoint pen ink in a variety of enclosure types that ultimately culminated in the development of a new method to detect color shift in documents with light sensitive media. This article offers instructions on how to detect color shift in digitized materials using Photoshop® Assisted Spectroscopy.

Precise X-Ray spectroscopy of the hydrogenlike and heliumlike heavy ions and of the exotic atoms

International Nuclear Information System (INIS)

Manil, B.

2001-10-01

In this thesis, we present four experiments designed to study hydrogenlike and heliumlike heavy ions, or exotic atoms. These experiments have been run at the Gesellschaft fur Schwerionenforchung (GSI) and the Paul Scherrer Institut (PSI). In the first part of this text, we begin with the description of a focusing, curved-crystal spectrometer in transmission geometry, coupled with a microstrip, germanium position-sensitive detector, which diffract X-ray photons in the range 50-100 keV. With this spectrometer, which can be mounted on the GSI accelerator, we will increase, by one order of magnitude, the accuracy on the measurement of the 1 s Lamb shift in hydrogenlike uranium ions, in order to test QED in strong coulomb field. Next, we detail an experiment that will soon give a new value of the charged-pion mass with a relative accuracy of 1 ppm. For that, we perform X-ray spectroscopy of pionic nitrogen, at PSI. The experimental set-up is made up of a cyclotron trap, a spherical Bragg-crystal focusing spectrometer, in reflection geometry, and a CCD sensitive-position cooled detector. This set-up allows also test QCD and chiral perturbation theory by measurements of radiative transitions of pionic hydrogen. The main subject of the second part is a lifetime measurement of the metastable 2 3 P 0 state in heliumlike gold ions, by Beam Foil Spectroscopy. With this experiment, which provides an important test of relativistic many-body theory, we give, for the first time, an accurate value of the lifetime of this state for an ion with a Z larger than 64, our result is τ(exp) = (22.12 ± 1.21) ps

Emerging science and technology of antimatter plasmas and trap-based beams

International Nuclear Information System (INIS)

Surko, C.M.; Greaves, R.G.

2004-01-01

Progress in the ability to accumulate and cool positrons and antiprotons is enabling new scientific and technological opportunities. The driver for this work is plasma physics research - developing new ways to create and manipulate antimatter plasmas. An overview is presented of recent results and near-term goals and challenges. In atomic physics, new experiments on the resonant capture of positrons by molecules provide the first direct evidence that positrons bind to 'ordinary' matter (i.e., atoms and molecules). The formation of low-energy antihydrogen was observed recently by injecting low-energy antiprotons into a cold positron plasma. This opens up a range of new scientific opportunities, including precision tests of fundamental symmetries such as invariance under charge conjugation, parity, and time reversal, and study of the chemistry of matter and antimatter. The first laboratory study of electron-positron plasmas has been conducted by passing an electron beam through a positron plasma. The next major step in these studies will be the simultaneous confinement of electron and positron plasmas. Although very challenging, such experiments would permit studies of the nonlinear behavior predicted for this unique and interesting plasma system. The use of trap-based positron beams to study transport in fusion plasmas and to characterize materials is reviewed. More challenging experiments are described, such as the creation of a Bose-condensed gas of positronium atoms. Finally, the future of positron trapping and beam formation is discussed, including the development of a novel multicell trap to increase by orders of magnitude the number of positrons trapped, portable antimatter traps, and cold antimatter beams (e.g., with energy spreads ≤1 meV) for precision studies of positron-matter interactions

Electric field effect on the emission rate of H4F and H4S hole traps in InP

International Nuclear Information System (INIS)

Darwich, R.; Alek, B.

2010-01-01

The electric field effect on the emission rate enhancement of the H4 F and H4 S hole trap in highly Zn-doped InP has been examined using the deep level transient spectroscopy (DLTS) and double correlation DLTS (DDLTS). The DLTS and DDLTS results have been found to be in good agreement for low and intermediate electric fields, but they disagree for large field effect. Comparing our emission data with the theory, we have found that H4 F obeys the quantum model of phonon-assisted tunneling while H4 S follows the Poole-Frenkel model employing a three-dimensional screening coulombic potential. Our results show that the H4 S defect can be attributed to a charged (V p - Zn) complex. (author)

Absorption spectra of trapped holes in anatase TiO2

DEFF Research Database (Denmark)

Zawadzki, Pawel

2013-01-01

absorption spectroscopy (TAS), but the understanding of the optical absorption due to trapped carriers in TiO2 is incomplete. On the basis of the generalized Δ self-consistent field density functional theory (Δ-SCF DFT) calculations, we attribute the experimentally observed absorption band at 430-550 nm...

Precision spectroscopy of the 2S-4P{sub 1/2} transition in atomic hydrogen on a cold thermal beam of optically excited 2S atoms

Energy Technology Data Exchange (ETDEWEB)

Beyer, Axel; Kolachevsky, Nikolai; Alnis, Janis; Yost, Dylan C.; Matveev, Arthur; Parthey, Christian G.; Pohl, Randolf; Udem, Thomas [Max-Planck-Institut fuer Quantenoptik, 85748 Garching (Germany); Khabarova, Ksenia [FSUE ' VNIIFTRI' , 141570 Moscow (Russian Federation); Haensch, Theodor W. [Max-Planck-Institut fuer Quantenoptik, 85748 Garching (Germany); Ludwig-Maximilians-Universitaet, 80799 Muenchen (Germany)

2013-07-01

The 'proton size puzzle', i.e. the discrepancy between the values for the proton r.m.s. charge radius deduced from precision spectroscopy of atomic hydrogen and electron-proton-scattering on one side and the value deduced from muonic hydrogen spectroscopy on the other side, has been persisting for more than two years now. Although huge efforts have been put into trying to resolve this discrepancy from experimental and theoretical side, no convincing argument could be found so far. In this talk, we report on a unique precision spectroscopy experiment on atomic hydrogen, which is aiming to bring some light to the hydrogen part of the puzzle: In contrast to any previous high resolution experiment probing a transition frequency between the meta-stable 2S state and a higher lying nL state (n=3,4,6,8,12, L=S,P,D), our measurement of the 2S-4P{sub 1/2} transition frequency is the first experiment being performed on a cold thermal beam of hydrogen atoms optically excited to the 2S state. We will discuss how this helps to efficiently suppresses leading systematic effects of previous measurements and present the preliminary results we obtained so far.

tweezercalib 2.0: Faster version of MatLab package for precise calibration of optical tweezers

DEFF Research Database (Denmark)

Hansen, Poul Martin; Tolic-Nørrelykke, Iva Marija; Flyvbjerg, Henrik

2006-01-01

We present a vectorized version of the MatLab (MathWorks Inc) package tweezercalib for calibration of optical tweezers with precision. The calibration is based on the power spectrum of the Brownian motion of a dielectric bead trapped in the tweezers. Precision is achieved by accounting for a number...

A metastable helium trap for atomic collision physics

International Nuclear Information System (INIS)

Colla, M.; Gulley, R.; Uhlmann, L.; Hoogerland, M.D.; Baldwin, K.G.H.; Buckman, S.J.

1999-01-01

Full text: Metastable helium in the 2 3 S state is an important species for atom optics and atomic collision physics. Because of its large internal energy (20eV), long lifetime (∼8000s) and large collision cross section for a range of processes, metastable helium plays an important role in atmospheric physics, plasma discharges and gas laser physics. We have embarked on a program of studies on atom-atom and electron-atom collision processes involving cold metastable helium. We confine metastable helium atoms in a magneto-optic trap (MOT), which is loaded by a transversely collimated, slowed and 2-D focussed atomic beam. We employ diode laser tuned to the 1083 nm (2 3 S 1 - 2 3 P2 1 ) transition to generate laser cooling forces in both the loading beam and the trap. Approximately 10 million helium atoms are trapped at temperatures of ∼ 1mK. We use phase modulation spectroscopy to measure the trapped atomic density. The cold, trapped atoms can collide to produce either atomic He + or molecular He 2 + ions by Penning Ionisation (PI) or Associative Ionisation (AI). The rate of formation of these ions is dependant upon the detuning of the trapping laser from resonance. A further laser can be used to connect the 2 3 S 1 state to another higher lying excited state, and variation of the probe laser detuning used to measure interatomic collision potential. Electron-atom collision processes are studied using a monochromatic electron beam with a well defined spatial current distribution. The total trap loss due to electron collisions is measured as a function of electron energy. Results will be presented for these atomic collision physics measurements involving cold, trapped metastable helium atoms. Copyright (1999) Australian Optical Society

Constraints on extra dimensions from precision molecular spectroscopy

NARCIS (Netherlands)

Salumbides, E.J.; Schellekens, A.N.; Gato-Rivera, B.; Ubachs, W.M.G.

2015-01-01

Accurate investigations of quantum-level energies in molecular systems are shown to provide a testing ground to constrain the size of compactified extra dimensions. This is made possible by recent progress in precision metrology with ultrastable lasers on energy levels in neutral molecular hydrogen

Forbidden atomic transitions driven by an intensity-modulated laser trap.

Science.gov (United States)

Moore, Kaitlin R; Anderson, Sarah E; Raithel, Georg

2015-01-20

Spectroscopy is an essential tool in understanding and manipulating quantum systems, such as atoms and molecules. The model describing spectroscopy includes the multipole-field interaction, which leads to established spectroscopic selection rules, and an interaction that is quadratic in the field, which is not often employed. However, spectroscopy using the quadratic (ponderomotive) interaction promises two significant advantages over spectroscopy using the multipole-field interaction: flexible transition rules and vastly improved spatial addressability of the quantum system. Here we demonstrate ponderomotive spectroscopy by using optical-lattice-trapped Rydberg atoms, pulsating the lattice light and driving a microwave atomic transition that would otherwise be forbidden by established spectroscopic selection rules. This ability to measure frequencies of previously inaccessible transitions makes possible improved determinations of atomic characteristics and constants underlying physics. The spatial resolution of ponderomotive spectroscopy is orders of magnitude better than the transition frequency would suggest, promising single-site addressability in dense particle arrays for quantum computing applications.

A microfluidic device integrating plasmonic nanodevices for Raman spectroscopy analysis on trapped single living cells

KAUST Repository

Perozziello, Gerardo; Catalano, Rossella; Francardi, Marco; Rondanina, Eliana; Pardeo, Francesca; De Angelis, Francesco De; Malara, Natalia Maria; Candeloro, Patrizio; Morrone, Giovanni; Di Fabrizio, Enzo M.

2013-01-01

In this work we developed a microfluidic device integrating nanoplasmonic devices combined with fluidic trapping regions. The microfuidic traps allow to capture single cells in areas where plasmonic sensors are placed. In this way it is possible to perform Enhanced Raman analysis on the cell membranes. Moreover, by changing direction of the flux it is possible to change the orientation of the cell in the trap, so that it is possible to analyze different points of the membrane of the same cell. We shows an innovative procedure to fabricate and assembly the microfluidic device which combine photolithography, focused ion beam machining, and hybrid bonding between a polymer substrate and lid of Calcium fluoride. This procedure is compatible with the fabrication of the plasmonic sensors in close proximity of the microfluidic traps. Moreover, the use of Calcium fluoride as lid allows full compatibility with Raman measurements producing negligible Raman background signal and avoids Raman artifacts. Finally, we performed Raman analysis on cells to monitor their oxidative stress under particular non physiological conditions. © 2013 Elsevier B.V. All rights reserved.

A microfluidic device integrating plasmonic nanodevices for Raman spectroscopy analysis on trapped single living cells

KAUST Repository

Perozziello, Gerardo

2013-11-01

In this work we developed a microfluidic device integrating nanoplasmonic devices combined with fluidic trapping regions. The microfuidic traps allow to capture single cells in areas where plasmonic sensors are placed. In this way it is possible to perform Enhanced Raman analysis on the cell membranes. Moreover, by changing direction of the flux it is possible to change the orientation of the cell in the trap, so that it is possible to analyze different points of the membrane of the same cell. We shows an innovative procedure to fabricate and assembly the microfluidic device which combine photolithography, focused ion beam machining, and hybrid bonding between a polymer substrate and lid of Calcium fluoride. This procedure is compatible with the fabrication of the plasmonic sensors in close proximity of the microfluidic traps. Moreover, the use of Calcium fluoride as lid allows full compatibility with Raman measurements producing negligible Raman background signal and avoids Raman artifacts. Finally, we performed Raman analysis on cells to monitor their oxidative stress under particular non physiological conditions. © 2013 Elsevier B.V. All rights reserved.

Correlation of a generation-recombination center with a deep level trap in GaN

International Nuclear Information System (INIS)

Nguyen, X. S.; Lin, K.; Zhang, Z.; Arehart, A. R.; Ringel, S. A.; McSkimming, B.; Speck, J. S.; Fitzgerald, E. A.; Chua, S. J.

2015-01-01

We report on the identification of a deep level trap centre which contributes to generation-recombination noise. A n-GaN epilayer, grown by MOCVD on sapphire, was measured by deep level transient spectroscopy (DLTS) and noise spectroscopy. DLTS found 3 well documented deep levels at E c  − 0.26 eV, E c  − 0.59 eV, and E c  − 0.71 eV. The noise spectroscopy identified a generation recombination centre at E c  − 0.65 ± 0.1 eV with a recombination lifetime of 65 μs at 300 K. This level is considered to be the same as the one at E c  − 0.59 eV measured from DLTS, as they have similar trap densities and capture cross section. This result shows that some deep levels contribute to noise generation in GaN materials

Nuclear laser spectroscopy with on-line ion traps

International Nuclear Information System (INIS)

Wada, M.; Nakamura, T.; Ohtani, S.

1996-01-01

The hyperfine structure of atoms informs us various static characteristics of nuclei, particularly for electro-magnetic moments and their distributions. We have been developing an experimental method to perform laser-microwave double-resonance spectroscopy for the hyperfine structure of Be and Ca isotopes, including unstable nuclei. The purpose and the status of the experiments are described. (orig.)

Volume traps - a new retrospective radon monitor

International Nuclear Information System (INIS)

Oberstedt, S.; Vanmarcke, H.

1994-11-01

A new method to trace back average radon concentrations in dwellings over several decades in time has been developed. This retrospective radon monitor is based on the measurement of the alpha activity of 210 Po deposited in volume traps, for example spongy materials used for mattresses and cushions. Polyester samples with different densities have been exposed to radon-laden air. The exposures correspond to characteristic radon concentrations between 390 Bq/m 3 and 3.9 Bq/m 3 over a 20 years period. The precision in converting the 210 Po signal to the radon exposure has been improved by more than one order of magnitude compared to other common techniques. It is shown that this very sensitive method may be applied to almost all types of volume traps used in households

Thermally assisted OSL from deep traps in Al2O3:C

International Nuclear Information System (INIS)

Polymeris, G.S.; Raptis, S.; Afouxenidis, D.; Tsirliganis, N.C.; Kitis, G.

2010-01-01

The present work suggests an alternative experimental method in order to not only measure the signal of the deep traps in Al 2 O 3 :C without heating the sample to temperatures greater than 500 o C, but also use this signal for high dose level dosimetry purposes as well. This method consists of photo transfer OSL measurements performed at elevated temperatures using the blue LEDs (470 nm, FWHM 20 nm) housed at commercial Riso TL/OSL systems, after the sample was previously heated up to 500 o C in order to empty its main TL dosimetric trap. The influence of this procedure on specific features such as glow curve shape and sensitivity of the main TL glow peak was also studied.

Atom interferometry with trapped Bose-Einstein condensates: impact of atom-atom interactions

International Nuclear Information System (INIS)

Grond, Julian; Hohenester, Ulrich; Mazets, Igor; Schmiedmayer, Joerg

2010-01-01

Interferometry with ultracold atoms promises the possibility of ultraprecise and ultrasensitive measurements in many fields of physics, and is the basis of our most precise atomic clocks. Key to a high sensitivity is the possibility to achieve long measurement times and precise readout. Ultracold atoms can be precisely manipulated at the quantum level and can be held for very long times in traps; they would therefore be an ideal setting for interferometry. In this paper, we discuss how the nonlinearities from atom-atom interactions, on the one hand, allow us to efficiently produce squeezed states for enhanced readout and, on the other hand, result in phase diffusion that limits the phase accumulation time. We find that low-dimensional geometries are favorable, with two-dimensional (2D) settings giving the smallest contribution of phase diffusion caused by atom-atom interactions. Even for time sequences generated by optimal control, the achievable minimal detectable interaction energy ΔE min is of the order of 10 -4 μ, where μ is the chemical potential of the Bose-Einstein condensate (BEC) in the trap. From these we have to conclude that for more precise measurements with atom interferometers, more sophisticated strategies, or turning off the interaction-induced dephasing during the phase accumulation stage, will be necessary.

Dislocation-related trap levels in nitride-based light emitting diodes

Energy Technology Data Exchange (ETDEWEB)

Venturi, Giulia; Castaldini, Antonio; Cavallini, Anna [Department of Physics and Astronomy, University of Bologna, Viale Berti Pichat 6/2, Bologna 40127 (Italy); Meneghini, Matteo; Zanoni, Enrico [Department of Information Engineering, University of Padova, via Gradenigo 6/B, Padova 35131 (Italy); Zhu, Dandan; Humphreys, Colin [Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom)

2014-05-26

Deep level transient spectroscopy was performed on InGaN/GaN multiple quantum well light emitting diodes (LEDs) in order to determine the effect of the dislocation density on the deep intragap electronic levels. The LEDs were grown by metalorganic vapor phase epitaxy on GaN templates with a high dislocation density of 8 × 10{sup 9} cm{sup −2} and a low dislocation density of 3 × 10{sup 8} cm{sup −2}. Three trapping levels for electrons were revealed, named A, A1, and B, with energies E{sub A} ≈ 0.04 eV, E{sub A1} ≈ 0.13 eV, and E{sub B} ≈ 0.54 eV, respectively. The trapping level A has a much higher concentration in the LEDs grown on the template with a high density of dislocations. The logarithmic dependence of the peak amplitude on the bias pulse width for traps A and A1 identifies the defects responsible for these traps as associated with linearly arranged defects. We conclude that traps A and A1 are dislocation-related intragap energy levels.

Dislocation-related trap levels in nitride-based light emitting diodes

International Nuclear Information System (INIS)

Venturi, Giulia; Castaldini, Antonio; Cavallini, Anna; Meneghini, Matteo; Zanoni, Enrico; Zhu, Dandan; Humphreys, Colin

2014-01-01

Deep level transient spectroscopy was performed on InGaN/GaN multiple quantum well light emitting diodes (LEDs) in order to determine the effect of the dislocation density on the deep intragap electronic levels. The LEDs were grown by metalorganic vapor phase epitaxy on GaN templates with a high dislocation density of 8 × 10 9 cm −2 and a low dislocation density of 3 × 10 8 cm −2 . Three trapping levels for electrons were revealed, named A, A1, and B, with energies E A  ≈ 0.04 eV, E A1  ≈ 0.13 eV, and E B  ≈ 0.54 eV, respectively. The trapping level A has a much higher concentration in the LEDs grown on the template with a high density of dislocations. The logarithmic dependence of the peak amplitude on the bias pulse width for traps A and A1 identifies the defects responsible for these traps as associated with linearly arranged defects. We conclude that traps A and A1 are dislocation-related intragap energy levels.

Trap assisted space charge conduction in p-NiO/n-ZnO heterojunction diode

Energy Technology Data Exchange (ETDEWEB)

Tyagi, Manisha [Department of Physics and Astrophysics, University of Delhi, Delhi-110007 (India); Tomar, Monika [Physics department, Miranda House, University of Delhi, Delhi-110007 (India); Gupta, Vinay, E-mail: drguptavinay@gmail.com [Department of Physics and Astrophysics, University of Delhi, Delhi-110007 (India)

2015-06-15

Highlights: • p-NiO/n-ZnO heterojunction diode with enhanced junction parameters has been prepared. • Temperature dependent I–V throw insight into the involved conduction mechanism. • SCLC with exponential trap distribution was found to be the dominant mechanism. • C–V measurement at different frequencies support the presence of traps. - Abstract: The development of short-wavelength p–n junction is essentially important for the realization of transparent electronics for next-generation optoelectronic devices. In the present work, a p–n heterojunction diode based on p-NiO/n-ZnO has been prepared under the optimised growth conditions exhibiting improved electrical and junction parameters. The fabricated heterojunction gives typical current–voltage (I–V) characteristics with good rectifying behaviour (rectification ratio ≈ 10{sup 4} at 2 V). The temperature dependent current–voltage characteristics of heterojunction diode have been studied and origin of conduction mechanism is identified. The space-charge limited conduction with exponential trap distribution having deep level trap is found to be the dominant conduction mechanism in the fabricated p–n heterojunction diode. The conduction and valence band discontinuities for NiO/ZnO heterostructure have been determined from the capacitance–voltage (C–V) measurements.

Spectroscopy of deep doping levels in Cd0.99Mn0.01Te:Ga

International Nuclear Information System (INIS)

Szatkowski, J.; Placzek-Popko, E.; Sieranski, K.; Bieg, B.

1997-01-01

The investigation results of deep energy levels in Cd 0.99 Mn 0.01 Te (n-type) doped with gallium have been presented. Deep level transient spectroscopy (DLTS) measurements have been carried out in temperature range 80-420 K. The results show five types of electron traps. The activation energy of trapping levels and electron trapping cross-sections have been determined for observed traps. 2 refs, 3 figs, 1 tab

Precision spectroscopy with ultracold 87Rb2 triplet molecules

International Nuclear Information System (INIS)

Strauss, Christoph

2011-01-01

In this thesis I report precision spectroscopy with ultracold 87 Rb 2 triplet molecules where we use lasers to couple the states in different molecular potentials. We study in detail states of the a 3 sum + u and (1) 3 sum + g potentials. These states are of great importance for transferring weakly bound molecules to the ro-vibrational triplet ground state via states of the excited potential. As most experiments start from molecules in their X 1 sum + g ground state, the triplet states were hard to access via dipole transitions and remained largely unexplored. The measurements presented in this thesis are the first detailed study of diatomic 87 Rb 2 molecules in these states. Our experiments start with an ultracold cloud of 87 Rb atoms. We then load this cloud into an optical lattice where we use a magnetic Feshbach resonance at 1007.4 G to perform a Feshbach association. After we have removed all unbound atoms, we end up with a pure sample of weakly bound Feshbach molecules inside the optical lattice. The optical lattice prevents these molecules from colliding with each other which results in molecular lifetimes on the order of a few hundred milliseconds. In the first set of experiments, we use a laser coupling the Feshbach state to the excited (1) 3 sum + g triplet state to map out its low-lying vibrational (v = 0.. 15), rotational, hyperfine, and Zeeman structure. The experimental results are in good agreement with calculations done by Marius Lysebo and Prof. Leif Veseth. We then map out in detail the vibrational, rotational, hyperfine, and Zeeman structure of the a 3 sum + u triplet ground state using dark state spectroscopy with levels in the (1) 3 sum + g potential as an intermediate state. In this scheme we are able to access molecules in triplet states because our Feshbach state has strong triplet character. Interestingly, it happens that some deeply bound states which belong to the X 1 sum + g potential are close to levels in the a 3 sum + u potential. In

Antihydrogen Experiment Gravity Interferometry Spectroscopy

CERN Multimedia

Trezzi, D; Dassa, L; Rienacker, B; Khalidova, O; Ferrari, G; Krasnicky, D; Perini, D; Cerchiari, G; Belov, A; Boscolo, I; Sacerdoti, M G; Ferragut, R O; Nedelec, P; Hinterberger, A; Al-qaradawi, I; Malbrunot, C L S; Brusa, R S; Prelz, F; Manuzio, G; Riccardi, C; Fontana, A; Genova, P; Haider, S; Haug, F; Turbabin, A; Castelli, F; Testera, G; Lagomarsino, V E; Doser, M; Penasa, L; Gninenko, S; Cataneo, F; Zenoni, A; Cabaret, L; Comparat, D P; Zmeskal, J; Scampoli, P; Nesteruk, K P; Dudarev, A; Kellerbauer, A G; Mariazzi, S; Carraro, C; Zavatarelli, S M

The AEGIS experiment (Antihydrogen Experiment: Gravity, Interferometry, Spectroscopy) has the aim of carrying out the first measurement of the gravitational interaction of antimatter to a precision of 1%, by applying techniques from atomic physics, laser spectroscopy and interferometry to a beam of antihydrogen atoms. A further goal of the experiment is to carry out spectroscopy of the antihydrogen atoms in flight.

High-precision mass measurements of nickel, copper, and gallium isotopes and the purported shell closure at N=40

International Nuclear Information System (INIS)

Guenaut, C.; Audi, G.; Beck, D.

2007-01-01

High-precision mass measurement of more than thirty neutron-rich nuclides around the Z=28 closed proton shell were performed with the triple-trap mass spectrometer ISOLTRAP at ISOLDE/CERN to address the question of a possible neutron shell closure at N=40. The results for 57,60,64-69 Ni, 65-74,76 Cu (Z=29), and 63-65,68-78 Ga (Z=31), have a relative uncertainty of the order of 10 -8 . In particular, the masses of 72-74,76 Cu have been measured for the first time. We analyse the resulting mass surface for signs of magicity, comparing the behavior of N=40 to that of known magic numbers and to mid-shell behavior. Contrary to nuclear spectroscopy studies, no indications of a shell or sub-shell closure are found for N=40. (authors)

Dependence of loading time on control parameters in a standard vapour—loaded magneto—optical trap

International Nuclear Information System (INIS)

Zhang Yi-Chi; Wu Ji-Zhou; Li Yu-Qing; Ma Jie; Wang Li-Rong; Zhao Yan-Ting; Xiao Lian-Tuan; Jia Suo-Tang

2011-01-01

Loading time is one of the most important dynamic characteristics of a magneto—optical trap. In this paper, we primarily report on a detailed experimental study of the effects of some magneto—optical trap control parameters on loading time, including the background vacuum pressure, the magnetic field gradient, and the intensities of trapping and repumping lasers. We compare the results with previous theoretical and experimental results, and give qualitative analysis. These experimental investigations offer some useful guidelines to control the loading time of magneto—optical traps. The controllable loading time achieved is helpful to enhance the signal-to-noise ratio of photoassociation spectroscopy, which is remarkably improved from 7 to 28.6. (atomic and molecular physics)

Manipulating Neutral Atoms in Chip-Based Magnetic Traps

Science.gov (United States)

Aveline, David; Thompson, Robert; Lundblad, Nathan; Maleki, Lute; Yu, Nan; Kohel, James

2009-01-01

Several techniques for manipulating neutral atoms (more precisely, ultracold clouds of neutral atoms) in chip-based magnetic traps and atomic waveguides have been demonstrated. Such traps and waveguides are promising components of future quantum sensors that would offer sensitivities much greater than those of conventional sensors. Potential applications include gyroscopy and basic research in physical phenomena that involve gravitational and/or electromagnetic fields. The developed techniques make it possible to control atoms with greater versatility and dexterity than were previously possible and, hence, can be expected to contribute to the value of chip-based magnetic traps and atomic waveguides. The basic principle of these techniques is to control gradient magnetic fields with suitable timing so as to alter a trap to exert position-, velocity-, and/or time-dependent forces on atoms in the trap to obtain desired effects. The trap magnetic fields are generated by controlled electric currents flowing in both macroscopic off-chip electromagnet coils and microscopic wires on the surface of the chip. The methods are best explained in terms of examples. Rather than simply allowing atoms to expand freely into an atomic waveguide, one can give them a controllable push by switching on an externally generated or a chip-based gradient magnetic field. This push can increase the speed of the atoms, typically from about 5 to about 20 cm/s. Applying a non-linear magnetic-field gradient exerts different forces on atoms in different positions a phenomenon that one can exploit by introducing a delay between releasing atoms into the waveguide and turning on the magnetic field.

High-resolution in-source laser spectroscopy in perpendicular geometry

Energy Technology Data Exchange (ETDEWEB)

Heinke, R., E-mail: reinhard.heinke@uni-mainz.de; Kron, T. [Universität Mainz, Institut für Physik (Germany); Raeder, S. [Helmholtz-Institut Mainz (Germany); Reich, T.; Schönberg, P. [Universität Mainz, Institut für Kernchemie (Germany); Trümper, M.; Weichhold, C.; Wendt, K. [Universität Mainz, Institut für Physik (Germany)

2017-11-15

Operation of the novel laser ion source unit LIST (Laser Ion Source and Trap), operating at the on-line radioactive ion beam facility ISOLDE at CERN allowed for the production of ultra-pure beams of exotic isotopes far-off stability as well as direct isobar-free laser spectroscopy, giving access to the study of atomic and nuclear properties of so far inaccessible nuclides. We present a specific upgrade and adaption of the LIST targeted for high resolution spectroscopy with a Doppler-reduced perpendicular atom - laser beam geometry. With this PI-LIST (Perpendicularly Illuminated Laser Ion Source and Trap) setup, experimental linewidths below 100 MHz could be demonstrated in optical laser spectroscopy off-line, applying a pulsed injection-locked high repetition rate Ti:sapphire laser. A dual repeller configuration ensured highest suppression of isobaric interferences and almost background-free measurements on small samples in the order of 10{sup 11} atoms.

Nest Mosquito Trap quantifies contact rates between nesting birds and mosquitoes.

Science.gov (United States)

Caillouët, Kevin A; Riggan, Anna E; Rider, Mark; Bulluck, Lesley P

2012-06-01

Accurate estimates of host-vector contact rates are required for precise determination of arbovirus transmission intensity. We designed and tested a novel mosquito collection device, the Nest Mosquito Trap (NMT), to collect mosquitoes as they attempt to feed on unrestrained nesting birds in artificial nest boxes. In the laboratory, the NMT collected nearly one-third of the mosquitoes introduced to the nest boxes. We then used these laboratory data to estimate our capture efficiency of field-collected bird-seeking mosquitoes collected over 66 trap nights. We estimated that 7.5 mosquitoes per trap night attempted to feed on nesting birds in artificial nest boxes. Presence of the NMT did not have a negative effect on avian nest success when compared to occupied nest boxes that were not sampled with the trap. Future studies using the NMT may elucidate the role of nestlings in arbovirus transmission and further refine estimates of nesting bird and vector contact rates. © 2012 The Society for Vector Ecology.

Microwave quantum logic gates for trapped ions.

Science.gov (United States)

Ospelkaus, C; Warring, U; Colombe, Y; Brown, K R; Amini, J M; Leibfried, D; Wineland, D J

2011-08-10

Control over physical systems at the quantum level is important in fields as diverse as metrology, information processing, simulation and chemistry. For trapped atomic ions, the quantized motional and internal degrees of freedom can be coherently manipulated with laser light. Similar control is difficult to achieve with radio-frequency or microwave radiation: the essential coupling between internal degrees of freedom and motion requires significant field changes over the extent of the atoms' motion, but such changes are negligible at these frequencies for freely propagating fields. An exception is in the near field of microwave currents in structures smaller than the free-space wavelength, where stronger gradients can be generated. Here we first manipulate coherently (on timescales of 20 nanoseconds) the internal quantum states of ions held in a microfabricated trap. The controlling magnetic fields are generated by microwave currents in electrodes that are integrated into the trap structure. We also generate entanglement between the internal degrees of freedom of two atoms with a gate operation suitable for general quantum computation; the entangled state has a fidelity of 0.76(3), where the uncertainty denotes standard error of the mean. Our approach, which involves integrating the quantum control mechanism into the trapping device in a scalable manner, could be applied to quantum information processing, simulation and spectroscopy.

Single Atoms Preparation Using Light-Assisted Collisions

Directory of Open Access Journals (Sweden)

Yin Hsien Fung

2016-01-01

Full Text Available The detailed control achieved over single optically trapped neutral atoms makes them candidates for applications in quantum metrology and quantum information processing. The last few decades have seen different methods developed to optimize the preparation efficiency of single atoms in optical traps. Here we review the near-deterministic preparation of single atoms based on light-assisted collisions and describe how this method can be implemented in different trap regimes. The simplicity and versatility of the method makes it feasible to be employed in future quantum technologies such as a quantum logic device.

Spectroscopy of highly charged tungsten ions with Electron Beam Ion Traps

International Nuclear Information System (INIS)

Sakaue, Hiroyuki A.; Kato, Daiji; Morita, Shigeru; Murakami, Izumi; Yamamoto, Norimasa; Ohashi, Hayato; Yatsurugi, Junji; Nakamura, Nobuyuki

2013-01-01

We present spectra of highly charged tungsten ions in the extreme ultra-violet (EUV) by using electron beam ion traps. The electron energy dependence of spectra is investigated of electron energies from 490 to 1440 eV. Previously unreported lines are presented in the EUV range, and some of them are identified by comparing the wavelengths with theoretical calculations. (author)

Behavior of many ions in a Penning trap and results of the WITCH experiment

CERN Document Server

Porobic, Tomica

Precision measurements of the beta−neutrino angular correlation in nuclear beta-decay provide a unique window into the physics beyond the Standard model. The WITCH (Weak Interaction Trap for CHarged particles) experiment aims to measure this correlation, a(beta-nu), in order to impose a more stringent constraint on the exotic scalar current admixture in the beta-decay Hamiltonian. The apparatus is situated at CERN/ISOLDE laboratory and consists of a unique combination of a retardation spectrometer and two Penning traps, with one of them serving as a scattering-free source. This configuration is suited for a precise measurement of the energy spectrum of 35Ar recoiled daughter ions. The shape of the spectrum then allows a determination of a(beta-nu) and consequently of the presence or absence of a scalar current. Radioactive 35Ar ions are created at ISOLDE by impinging 1.2 GeV protons on the target material. After being separated by a magnetic separator and bunched by REXTRAP, a high-capacity Penning trap, th...

Recoil ion momentum spectroscopy in atomic and nuclear physics: applications to low energy ion-atom/molecule collisions and to beta-neutrino angular correlation in beta decay

International Nuclear Information System (INIS)

Flechard, X.

2012-12-01

Since the early 1990's, Recoil Ion Momentum Spectroscopy is an ideal tool for ion-atom and ion-molecule collisions study. We detail here the development of this experimental technique during the last twenty years, illustrated with some of the most striking results obtained at GANIL (Caen) and J.R. Mac Donald Laboratory (Kansas State University). Recoil Ion Momentum Spectroscopy is also particularly well suited for β-ν angular correlation measurements in nuclear β decay. The LPCTrap experiment, installed at GANIL, is based on this technique, coupled to the use of a Paul trap for the radioactive ions confinement. The precise measurements performed with this setup allow both, to test specific aspects of the Standard Model of elementary particles, and to study the electron shake-off process following β decay. (author)

Lamb-Dicke spectroscopy of atoms in a hollow-core photonic crystal fibre

Science.gov (United States)

Okaba, Shoichi; Takano, Tetsushi; Benabid, Fetah; Bradley, Tom; Vincetti, Luca; Maizelis, Zakhar; Yampol'skii, Valery; Nori, Franco; Katori, Hidetoshi

2014-01-01

Unlike photons, which are conveniently handled by mirrors and optical fibres without loss of coherence, atoms lose their coherence via atom–atom and atom–wall interactions. This decoherence of atoms deteriorates the performance of atomic clocks and magnetometers, and also hinders their miniaturization. Here we report a novel platform for precision spectroscopy. Ultracold strontium atoms inside a kagome-lattice hollow-core photonic crystal fibre are transversely confined by an optical lattice to prevent atoms from interacting with the fibre wall. By confining at most one atom in each lattice site, to avoid atom–atom interactions and Doppler effect, a 7.8-kHz-wide spectrum is observed for the 1S0−3P1(m=0) transition. Atoms singly trapped in a magic lattice in hollow-core photonic crystal fibres improve the optical depth while preserving atomic coherence time. PMID:24934478

Discovery of deep and shallow trap states from step structures of rutile TiO2 vicinal surfaces by second harmonic and sum frequency generation spectroscopy

International Nuclear Information System (INIS)

Takahashi, Hiroaki; Watanabe, Ryosuke; Miyauchi, Yoshihiro; Mizutani, Goro

2011-01-01

In this report, local electronic structures of steps and terraces on rutile TiO 2 single crystal faces were studied by second harmonic and sum frequency generation (SHG/SFG) spectroscopy. We attained selective measurement of the local electronic states of the step bunches formed on the vicinal (17 18 1) and (15 13 0) surfaces using a recently developed step-selective probing technique. The electronic structures of the flat (110)-(1x1) (the terrace face of the vicinal surfaces) and (011)-(2x1) surfaces were also discussed. The SHG/SFG spectra showed that step structures are mainly responsible for the formation of trap states, since significant resonances from the trap states were observed only from the vicinal surfaces. We detected deep hole trap (DHT) states and shallow electron trap (SET) states selectively from the step bunches on the vicinal surfaces. Detailed analysis of the SHG/SFG spectra showed that the DHT and SET states are more likely to be induced at the top edges of the step bunches than on their hillsides. Unlike the SET states, the DHT states were observed only at the step bunches parallel to [1 1 1][equivalent to the step bunches formed on the (17 18 1) surface]. Photocatalytic activity for each TiO 2 sample was also measured through methylene blue photodegradation reactions and was found to follow the sequence: (110) < (17 18 1) < (15 13 0) < (011), indicating that steps along [0 0 1] are more reactive than steps along [1 1 1]. This result implies that the presence of the DHT states observed from the step bunches parallel to [1 1 1] did not effectively contribute to the methylene blue photodegradation reactions.

Sympathetic cooling of ions in a hybrid atom ion trap

Energy Technology Data Exchange (ETDEWEB)

Hoeltkemeier, Bastian

2016-10-27

In this thesis the dynamics of a trapped ion immersed in a spatially localized buffer gas is investigated. For a homogeneous buffer gas, the ion's energy distribution reaches a stable equilibrium only if the mass of the buffer gas atoms is below a critical value. This limitation can be overcome by using multipole traps in combination and/or a spatially confined buffer gas. Using a generalized model for elastic collisions of the ion with the buffer gas atoms, the ion's energy distribution is numerically determined for arbitrary buffer gas distributions and trap parameters. Three regimes characterized by the respective analytic form of the ion's equilibrium energy distribution are found. One of these is a novel regime at large atom-to-ion mass ratios where the final ion temperature can tuned by adiabatically decreasing the spatial extension of the buffer gas and the effective ion trap depth (forced sympathetic cooling). The second part of the thesis presents a hybrid atom ion trap designed for sympathetic cooling of hydroxide anions. In this hybrid trap the anions are immersed in a cloud of laser cooled rubidium atoms. The translational and rovibrational temperatures of the anions is probed by photodetachment tomography and spectroscopy which shows the first ever indication of sympathetic cooling of anions by laser cooled atoms.

Improvements in the injection system of the Canadian Penning trap mass spectrometer

CERN Document Server

Clark, J; Boudreau, C; Buchinger, F; Crawford, J E; Gulick, S; Hardy, J C; Heinz, A; Lee, J K P; Moore, R B; Savard, G; Seweryniak, D; Sharma, K S; Sprouse, G; Vaz, J; Wang, J C; Zhou, Z

2003-01-01

The Canadian Penning Trap (CPT) mass spectrometer is designed to make precise mass measurements on a variety of stable and short-lived isotopes. Modifications to the injection system of the CPT have been implemented in recent months, the purpose being to more efficiently collect and transfer weakly-produced reaction products from the target to the Penning trap. These include a magnetic triplet situated after the target chamber to increase the acceptance of the Enge spectrograph, a velocity filter to more effectively separate the beam from the reaction products and the replacement of the Paul trap with a linear trap resulting in more efficient capture and accumulation of ions from the ion cooler. This paper will discuss these recent modifications and how they have increased our ability in making mass measurements on isotopes of low abundance, including those from a sup 2 sup 5 sup 2 Cf fission source.

Measurement of the neutron lifetime by counting trapped protons

International Nuclear Information System (INIS)

Byrne, J.; Dawber, P.G.; Spain, J.A.; Williams, A.P.; Dewey, M.S.; Gilliam, D.M.; Greene, G.L.; Lamaze, G.P.; Scott, R.D.; Pauwels, J.; Eykens, R.; Lamberty, A.

1990-01-01

The neutron lifetime τ n has been measured by counting decay protons stored in a Penning trap whose magnetic axis coincided with a neutron-beam axis. The result of the measurement is τ n =893.6±5.3 s, which agrees well with the value predicted by precise measurements of the β-decay asymmetry parameter A and the standard model

Optical resonator for a standing wave dipole trap for fermionic lithium atoms

International Nuclear Information System (INIS)

Elsaesser, T.

2000-01-01

This thesis reports on the the construction of an optical resonator for a new resonator dipole trap to store the fermionic 6 Li-isotope and to investigate its scattering properties. It was demonstrated that the resonator enhances the energy density of a (1064 nm and 40 mW) laser beam by a factor of more than 100. A fused silica vacuum cell is positioned inside the resonator under Brewster's angle. The losses of the resonator depend mainly on the optical quality of the cell. The expected trap depth of the dipole trap is 200 μK and the photon scattering rate is expected to be about 0.4 s -1 . The resonator is stabilized by means of a polarization spectroscopy method. Due to high trap frequencies, which are produced by the tight enclosure of the standing wave in the resonator, the axial motion must be quantized. A simple model to describe this quantization has been developed. A magneto-optical trap, which serves as a source of cold lithium atoms, was put in operation. (orig.)

Real-time analysis of δ13C- and δD-CH4 by high precision laser spectroscopy

Science.gov (United States)

Eyer, Simon; Emmenegger, Lukas; Tuzson, Béla; Fischer, Hubertus; Mohn, Joachim

2014-05-01

Methane (CH4) is the most important non-CO2 greenhouse gas (GHG) contributing 18% to total radiative forcing. Anthropogenic sources (e.g. ruminants, landfills) contribute 60% to total emissions and led to an increase in its atmospheric mixing ratio from 700 ppb in pre-industrial times to 1819 ± 1 ppb in 2012 [1]. Analysis of the most abundant methane isotopologues 12CH4, 13CH4 and 12CH3D can be used to disentangle the various source/sink processes [2] and to develop target oriented reduction strategies. High precision isotopic analysis of CH4 can be accomplished by isotope-ratio mass-spectrometry (IRMS) [2] and more recently by mid-infrared laser-based spectroscopic techniques. For high precision measurements in ambient air, however, both techniques rely on preconcentration of the target gas [3]. In an on-going project, we developed a fully-automated, field-deployable CH4 preconcentration unit coupled to a dual quantum cascade laser absorption spectrometer (QCLAS) for real-time analysis of CH4 isotopologues. The core part of the rack-mounted (19 inch) device is a highly-efficient adsorbent trap attached to a motorized linear drive system and enclosed in a vacuum chamber. Thereby, the adsorbent trap can be decoupled from the Stirling cooler during desorption for fast desorption and optimal heat management. A wide variety of adsorbents, including: HayeSep D, molecular sieves as well as the novel metal-organic frameworks and carbon nanotubes were characterized regarding their surface area, isosteric enthalpy of adsorption and selectivity for methane over nitrogen. The most promising candidates were tested on the preconcentration device and a preconcentration by a factor > 500 was obtained. Furthermore analytical interferants (e.g. N2O, CO2) are separated by step-wise desorption of trace gases. A QCL absorption spectrometer previously described by Tuzson et al. (2010) for CH4 flux measurements was modified to obtain a platform for high precision and simultaneous

Precision Medicine and Men's Health.

Science.gov (United States)

Mata, Douglas A; Katchi, Farhan M; Ramasamy, Ranjith

2017-07-01

Precision medicine can greatly benefit men's health by helping to prevent, diagnose, and treat prostate cancer, benign prostatic hyperplasia, infertility, hypogonadism, and erectile dysfunction. For example, precision medicine can facilitate the selection of men at high risk for prostate cancer for targeted prostate-specific antigen screening and chemoprevention administration, as well as assist in identifying men who are resistant to medical therapy for prostatic hyperplasia, who may instead require surgery. Precision medicine-trained clinicians can also let couples know whether their specific cause of infertility should be bypassed by sperm extraction and in vitro fertilization to prevent abnormalities in their offspring. Though precision medicine's role in the management of hypogonadism has yet to be defined, it could be used to identify biomarkers associated with individual patients' responses to treatment so that appropriate therapy can be prescribed. Last, precision medicine can improve erectile dysfunction treatment by identifying genetic polymorphisms that regulate response to medical therapies and by aiding in the selection of patients for further cardiovascular disease screening.

Numerical Analysis of Hydrodynamic Flow in Microfluidic Biochip for Single-Cell Trapping Application

Directory of Open Access Journals (Sweden)

Amelia Ahmad Khalili

2015-11-01

Full Text Available Single-cell analysis has become the interest of a wide range of biological and biomedical engineering research. It could provide precise information on individual cells, leading to important knowledge regarding human diseases. To perform single-cell analysis, it is crucial to isolate the individual cells before further manipulation is carried out. Recently, microfluidic biochips have been widely used for cell trapping and single cell analysis, such as mechanical and electrical detection. This work focuses on developing a finite element simulation model of single-cell trapping system for any types of cells or particles based on the hydrodynamic flow resistance (Rh manipulations in the main channel and trap channel to achieve successful trapping. Analysis is carried out using finite element ABAQUS-FEA™ software. A guideline to design and optimize single-cell trapping model is proposed and the example of a thorough optimization analysis is carried out using a yeast cell model. The results show the finite element model is able to trap a single cell inside the fluidic environment. Fluid’s velocity profile and streamline plots for successful and unsuccessful single yeast cell trapping are presented according to the hydrodynamic concept. The single-cell trapping model can be a significant important guideline in designing a new chip for biomedical applications.

A passion for precision

CERN Multimedia

CERN. Geneva

2006-01-01

For more than three decades, the quest for ever higher precision in laser spectroscopy of the simple hydrogen atom has inspired many advances in laser, optical, and spectroscopic techniques, culminating in femtosecond laser optical frequency combs  as perhaps the most precise measuring tools known to man. Applications range from optical atomic clocks and tests of QED and relativity to searches for time variations of fundamental constants. Recent experiments are extending frequency comb techniques into the extreme ultraviolet. Laser frequency combs can also control the electric field of ultrashort light pulses, creating powerful new tools for the emerging field of attosecond science.Organiser(s): L. Alvarez-Gaume / PH-THNote: * Tea & coffee will be served at 16:00.

Linear and Nonlinear Molecular Spectroscopy with Laser Frequency Combs

Science.gov (United States)

Picque, Nathalie

2013-06-01

The regular pulse train of a mode-locked femtosecond laser can give rise to a comb spectrum of millions of laser modes with a spacing precisely equal to the pulse repetition frequency. Laser frequency combs were conceived a decade ago as tools for the precision spectroscopy of atomic hydrogen. They are now becoming enabling tools for an increasing number of applications, including molecular spectroscopy. Recent experiments of multi-heterodyne frequency comb Fourier transform spectroscopy (also called dual-comb spectroscopy) have demonstrated that the precisely spaced spectral lines of a laser frequency comb can be harnessed for new techniques of linear absorption spectroscopy. The first proof-of-principle experiments have demonstrated a very exciting potential of dual-comb spectroscopy without moving parts for ultra-rapid and ultra-sensitive recording of complex broad spectral bandwidth molecular spectra. Compared to conventional Michelson-based Fourier transform spectroscopy, recording times could be shortened from seconds to microseconds, with intriguing prospects for spectroscopy of short lived transient species. The resolution improves proportionally to the measurement time. Therefore longer recordings allow high resolution spectroscopy of molecules with extreme precision, since the absolute frequency of each laser comb line can be known with the accuracy of an atomic clock. Moreover, since laser frequency combs involve intense ultrashort laser pulses, nonlinear interactions can be harnessed. Broad spectral bandwidth ultra-rapid nonlinear molecular spectroscopy and imaging with two laser frequency combs is demonstrated with coherent Raman effects and two-photon excitation. Real-time multiplex accessing of hyperspectral images may dramatically expand the range of applications of nonlinear microscopy. B. Bernhardt et al., Nature Photonics 4, 55-57 (2010); A. Schliesser et al. Nature Photonics 6, 440-449 (2012); T. Ideguchi et al. arXiv:1201.4177 (2012) T

Wavelength Selection Method Based on Differential Evolution for Precise Quantitative Analysis Using Terahertz Time-Domain Spectroscopy.

Science.gov (United States)

Li, Zhi; Chen, Weidong; Lian, Feiyu; Ge, Hongyi; Guan, Aihong

2017-12-01

Quantitative analysis of component mixtures is an important application of terahertz time-domain spectroscopy (THz-TDS) and has attracted broad interest in recent research. Although the accuracy of quantitative analysis using THz-TDS is affected by a host of factors, wavelength selection from the sample's THz absorption spectrum is the most crucial component. The raw spectrum consists of signals from the sample and scattering and other random disturbances that can critically influence the quantitative accuracy. For precise quantitative analysis using THz-TDS, the signal from the sample needs to be retained while the scattering and other noise sources are eliminated. In this paper, a novel wavelength selection method based on differential evolution (DE) is investigated. By performing quantitative experiments on a series of binary amino acid mixtures using THz-TDS, we demonstrate the efficacy of the DE-based wavelength selection method, which yields an error rate below 5%.

Precise atomic mass measurements by deflection mass spectrometry

CERN Document Server

Barber, R C

2003-01-01

Since its inception nearly 90 years ago by J.J. Thomson, the precise determination of atomic masses by the classical technique of deflecting charged particles in electric and magnetic fields has provided a large body of data on naturally occurring nuclides. Currently, such measurements on stable nuclides have frequently achieved a precision of better than two parts in 10 sup 9 of the mass. A review of the technique, together with a brief summary of the important historical developments in the field of precise atomic mass measurements, will be given. The more recent contributions to this field by the deflection mass spectrometer at the University of Manitoba will be provided as illustrations of the culmination of the techniques used and the applications that have been studied. A brief comparison between this and newer techniques using Penning traps will be presented.

Highly effective portable beta spectrometer for precise depth selective electron Moessbauer spectroscopy

International Nuclear Information System (INIS)

Aldiyarov, N.U.; Kadyrzhanov, K.K.; Seytimbetov, A.M.; Zhdanov, V.S.

2007-01-01

Full text: More broad application of the nuclear-physical method of precise Depth Selective Electron Moessbauer Spectroscopy (DS EMS) is limited by insufficient accessibility of highly-effective beta spectrometers with acceptable resolution. It should be mentioned that the method DS EMS is realized at a combined installation that consists of a highly-effective beta spectrometer and a conventional portable nuclear gamma-resonance spectrometer. Yet few available beta spectrometers have sophisticated design and controlling; in most cases they are cumbersome. All the attempts to simplify beta spectrometers resulted in noticeable worsening of depth resolution for the DS EMS method making the measurements non precise. There is currently an obvious need in a highly-effective portable easily controlled beta spectrometer. While developing such portable beta spectrometer, it is more promising to use as basis a simpler spectrometer, which has ratio of sample size to spectrometer size of about five times. The paper presents an equal-arm version of a highly-effective portable beta spectrometer with transverse heterogeneous sector magnetic field that assures double focusing. The spectrometer is equipped with a large-area non-equipotential source (a sample under investigation) and a position-sensitive detector. This portable spectrometer meets all requirements for achievement of the DS EMS depth resolution close to the physical limit and demonstrates the following main characteristics: equilibrium orbit radius ρ 0 = 80 mm, instrumental energy resolution 0.6 % at solid angle 1 % of 4π steradian, area of non-equipotential source ∼ 80 mm 2 , registration by position-sensitive detector of ∼ 10 % of the energy interval. Highly-effective portable beta spectrometer assures obtaining Moessbauer data with depth resolution close to physical limit of the DS EMS method. So in measurements at conversion and Auger electrons with energies of about units of keV and above, the achieved

Investigations of the ground-state hyperfine atomic structure and beta decay measurement prospects of 21Na with improved laser trapping techniques

International Nuclear Information System (INIS)

Rowe, Mary A.

1999-01-01

This thesis describes an experiment in which a neutral atom laser trap loaded with radioactive 21 Na was improved and then used for measurements. The sodium isotope (half-life=22 sec) is produced on line at the 88in cyclotron at Lawrence Berkeley National Laboratory. The author developed an effective magnesium oxide target system which is crucial to deliver a substantive beam of 21 Na to the experiment. Efficient manipulation of the 21 Na beam with lasers allowed 30,000 atoms to be contained in a magneto-optical trap. Using the cold trapped atoms, the author measured to high precision the hyperfine splitting of the atomic ground state of 21 Na. She measured the 3S 1/2 (F=1,m=0)-3S 1/2 (F=2,m=0) atomic level splitting of 21 Na to be 1,906,471,870±200 Hz. Additionally, she achieved initial detection of beta decay from the trap and evaluated the prospects of precision beta decay correlation studies with trapped atoms

Exploring strategies for the production of ultracold RbYb molecules in conservative traps

Energy Technology Data Exchange (ETDEWEB)

Bruni, Cristian

2015-07-14

Within the scope of this thesis, the production of ultracold molecules at a temperature of a few μK with various isotopes of rubidium (Rb) and ytterbium (Yb) was examined by means of photoassociation spectroscopy and magnetic Feshbach resonances in combined conservative traps. The long-term goal of this experiment is the production of ultracold RbYb molecules in the rovibronic ground state. It was possible to produce electronically excited {sup 87}Rb {sup 176}Yb molecules in a novel hybrid trap (HT) at a combined temperature of 1.7 μK by means of 1-photon photoassociation close to the Rb D1 line at 795 nm. This HT takes advantage of the different magnetic properties of Rb and Yb and allows for independent trapping and manipulation of the atomic species. It combines an Ioffe-Pritchard type magnetic trap for Rb and a near-resonant optical dipole trap for Yb. The excited molecular {sup 2}Π{sub 1/2} state could be characterized further extending previous works in a combined MOT and vibrational levels reaching binding energies up to E{sub b}=-h x 2.2 THz could be assigned by trap-loss spectroscopy. Almost every detected vibrational state consists of two resonances that could be assigned to the molecular analogue of the hyperfine structure of {sup 87}Rb. An important experimental observation is a decrease in hyperfine splitting with increasing binding energy of a vibrational level. For the deepest found vibrational state the hyperfine splitting amounts only 70 % of the atomic value (817 MHz) which emphasizes a gradual passage from weakly to tightly bound molecules. Furthermore, detailed attempts were undertaken to induce magnetic Feshbach resonances in {sup 85}Rb and different Yb isotopes, especially {sup 171}Yb in a crossed optical dipole trap at 1064 nm at temperatures of 10 μK. For this purpose, a homogeneous magnetic field was applied and scanned in small steps over the range of 495 G ∼ 640 G. Unfortunately, our efforts were without success. Additionally, well

Investigation of the proton-neutron interaction by high-precision nuclear mass measurements

CERN Multimedia

Savreux, R P; Akkus, B

2007-01-01

We propose to measure the atomic masses of a series of short-lived nuclides, including $^{70}$Ni, $^{122-130}$Cd, $^{134}$Sn, $^{138,140}$Xe, $^{207-210}$Hg, and $^{223-225}$Rn, that contribute to the investigation of the proton-neutron interaction and its role in nuclear structure. The high-precision mass measurements are planned for the Penning trap mass spectrometer ISOLTRAP that reaches the required precision of 10 keV in the nuclear mass determination.

Resonant quantum transitions in trapped antihydrogen atoms.

Science.gov (United States)

Amole, C; Ashkezari, M D; Baquero-Ruiz, M; Bertsche, W; Bowe, P D; Butler, E; Capra, A; Cesar, C L; Charlton, M; Deller, A; Donnan, P H; Eriksson, S; Fajans, J; Friesen, T; Fujiwara, M C; Gill, D R; Gutierrez, A; Hangst, J S; Hardy, W N; Hayden, M E; Humphries, A J; Isaac, C A; Jonsell, S; Kurchaninov, L; Little, A; Madsen, N; McKenna, J T K; Menary, S; Napoli, S C; Nolan, P; Olchanski, K; Olin, A; Pusa, P; Rasmussen, C Ø; Robicheaux, F; Sarid, E; Shields, C R; Silveira, D M; Stracka, S; So, C; Thompson, R I; van der Werf, D P; Wurtele, J S

2012-03-07

The hydrogen atom is one of the most important and influential model systems in modern physics. Attempts to understand its spectrum are inextricably linked to the early history and development of quantum mechanics. The hydrogen atom's stature lies in its simplicity and in the accuracy with which its spectrum can be measured and compared to theory. Today its spectrum remains a valuable tool for determining the values of fundamental constants and for challenging the limits of modern physics, including the validity of quantum electrodynamics and--by comparison with measurements on its antimatter counterpart, antihydrogen--the validity of CPT (charge conjugation, parity and time reversal) symmetry. Here we report spectroscopy of a pure antimatter atom, demonstrating resonant quantum transitions in antihydrogen. We have manipulated the internal spin state of antihydrogen atoms so as to induce magnetic resonance transitions between hyperfine levels of the positronic ground state. We used resonant microwave radiation to flip the spin of the positron in antihydrogen atoms that were magnetically trapped in the ALPHA apparatus. The spin flip causes trapped anti-atoms to be ejected from the trap. We look for evidence of resonant interaction by comparing the survival rate of trapped atoms irradiated with microwaves on-resonance to that of atoms subjected to microwaves that are off-resonance. In one variant of the experiment, we detect 23 atoms that survive in 110 trapping attempts with microwaves off-resonance (0.21 per attempt), and only two atoms that survive in 103 attempts with microwaves on-resonance (0.02 per attempt). We also describe the direct detection of the annihilation of antihydrogen atoms ejected by the microwaves.

Tightly confined atoms in optical dipole traps

International Nuclear Information System (INIS)

Schulz, M.

2002-12-01

trap depth. In a crossed beam geometry with red-detuned laser light, efficient transfer of atoms between the beams is observed. Optimum transfer occurs when the two beams cross at a radial offset, which can be qualitatively understood when the particle energy and geometrical properties of the two-beam trapping potential are considered. Numerical simulations reproduce the general features of the measured transfer efficiency vs. radial beam offset. Atoms have been radially confined in a blue-detuned hollow beam. This configuration is currently extended to a three-dimensionally confining blue-detuned dipole trap. For advanced laser cooling, state manipulation and spectroscopy, a double-diode laser system has been set up which is phase-locked with a difference frequency near 6.834 GHz to drive Raman transitions between the hyperfine-split ground states of Rb-87 atoms. Dark resonances with linewidths below 100-Hz have been observed in a buffer gas loaded rubidium vapour cell. (author)

Precision experiments with rare isotopes with LEBIT at MSU

Energy Technology Data Exchange (ETDEWEB)

Schury, P.; Bollen, G.; Ringle, R.; Sun, T. [National Superconducting Cyclotron Laboratory, East Lansing, MI (United States); Michigan State University, Department of Physics and Astronomy, East Lansing, MI (United States); Davies, D.A.; Morrissey, D.J. [National Superconducting Cyclotron Laboratory, East Lansing, MI (United States); Michigan State University, Department of Chemistry, East Lansing, MI (United States); Doemer, A.; Prinke, A. [Michigan State University, Department of Physics and Astronomy, East Lansing, MI (United States); Lawton, D.; Ottarson, J.; Schwarz, S.; Weissman, L. [National Superconducting Cyclotron Laboratory, East Lansing, MI (United States)

2005-09-01

The Low-Energy Beam and Ion Trap facility LEBIT at the NSCL is in the final phase of commissioning. Gas stopping of fast fragment beams and modern ion manipulation techniques are used to provide beams for high-precision mass measurements and other experiments. The status of the facility and the result of first test mass measurements on stable krypton isotopes are presented. (orig.)

On the investigation of electronic defect states in ZnO thin films by space charge spectroscopy with optical excitation

Science.gov (United States)

Schmidt, Matthias; Wenckstern, Holger von; Pickenhain, Rainer; Grundmann, Marius

2012-09-01

Electronic defect states in a n-type conducting zinc oxide thin film sample were investigated by means of space charge spectroscopy focussing on levels in the midgap region as well as on hole traps. To overcome the experimental difficulties arising from the wide bandgap and the lack of p-type conduction, optical excitation was employed to measure the emission of trapped charge carriers from these levels. Therefore - besides deep-level transient spectroscopy measurements - photo-capacitance, optically chopped photo-current, minority carrier transient spectroscopy, and optical capacitance-voltage experiments were conducted. In doing so, a midgap level labelled T4, and hole traps labelled TH1 and TH2 were detected. In the case of T4 and TH1 the photo-ionisation cross-section spectra were determined.

Chemical characterization of microparticles by laser ablation in an ion trap mass spectrometer

International Nuclear Information System (INIS)

Dale, J.M.; Whitten, W.B.; Ramsey, J.M.

1991-01-01

We are developing a new technique for the chemical characterization of microparticles based upon the use of electrodynamic traps. The electrodynamic trap has achieved widespread use in the mass spectrometry community in the form of the ion trap mass spectrometer or quadrupole ion trap. Small macroscopic particles can be confined or leviated within the electrode structure of a three-dimensional quadrupole electrodynamic trap in the same way as fundamental charges or molecular ions by using a combination of ac and dc potentials. Our concept is to use the same electrode structure to perform both microparticle levitation and ion trapping/mass analysis. The microparticle will first be trapped and spatially stabilized within the trap for characterization by optical probes, i.e., absorption, fluorescence, or Raman spectroscopy. After the particle has been optically characterized, it is further characterized using mass spectrometry. Ions are generated from the particle surface using laser ablation or desorption. The characteristics of the applied voltages are changed to trap the ions formed by the laser with the ions subsequently mass analyzed. The work described in this paper focuses on the ability to perform laser desorption experiments on microparticles contained within the ion trap. Laser desorption has previously been demonstrated in ion trap devices by applying the sample to a probe which is inserted so as to place the sample at the surface of the ring electrode. Our technique requires the placement of a microparticle in the center of the trap. Our initial experiments have been performed on falling microparticles rather than levitated particles to eliminate voltage switching requirements when changing from particle to ion trapping modes

Raman spectroscopy

Science.gov (United States)

Raman spectroscopy has gained increased use and importance in recent years for accurate and precise detection of physical and chemical properties of food materials, due to the greater specificity and sensitivity of Raman techniques over other analytical techniques. This book chapter presents Raman s...

Recent progress of laser spectroscopy experiments on antiprotonic helium

Science.gov (United States)

Hori, Masaki

2018-03-01

The Atomic Spectroscopy and Collisions Using Slow Antiprotons (ASACUSA) collaboration is currently carrying out laser spectroscopy experiments on antiprotonic helium ? atoms at CERN's Antiproton Decelerator facility. Two-photon spectroscopic techniques have been employed to reduce the Doppler width of the measured ? resonance lines, and determine the atomic transition frequencies to a fractional precision of 2.3-5 parts in 109. More recently, single-photon spectroscopy of buffer-gas cooled ? has reached a similar precision. By comparing the results with three-body quantum electrodynamics calculations, the antiproton-to-electron mass ratio was determined as ?, which agrees with the known proton-to-electron mass ratio with a precision of 8×10-10. The high-quality antiproton beam provided by the future Extra Low Energy Antiproton Ring (ELENA) facility should enable further improvements in the experimental precision. This article is part of the Theo Murphy meeting issue `Antiproton physics in the ELENA era'.

Detection and characterisation of radicals using electron paramagnetic resonance (EPR) spin trapping and related methods

DEFF Research Database (Denmark)

Davies, Michael Jonathan

2016-01-01

Electron paramagnetic resonance (EPR) spectroscopy (also known as electron spin resonance, ESR, or electron magnetic resonance, EMR, spectroscopy) is often described as the “gold standard” for the detection and characterisation of radicals in chemical, biological and medical systems. The article...... reviews aspects of EPR spectroscopy and discusses how this methodology and related techniques can be used to obtain useful information from biological systems. Consideration is given to the direct detection of radicals, the use of spin traps and the detection of nitric oxide, and the advantages...

Dissipative quantum error correction and application to quantum sensing with trapped ions.

Science.gov (United States)

Reiter, F; Sørensen, A S; Zoller, P; Muschik, C A

2017-11-28

Quantum-enhanced measurements hold the promise to improve high-precision sensing ranging from the definition of time standards to the determination of fundamental constants of nature. However, quantum sensors lose their sensitivity in the presence of noise. To protect them, the use of quantum error-correcting codes has been proposed. Trapped ions are an excellent technological platform for both quantum sensing and quantum error correction. Here we present a quantum error correction scheme that harnesses dissipation to stabilize a trapped-ion qubit. In our approach, always-on couplings to an engineered environment protect the qubit against spin-flips or phase-flips. Our dissipative error correction scheme operates in a continuous manner without the need to perform measurements or feedback operations. We show that the resulting enhanced coherence time translates into a significantly enhanced precision for quantum measurements. Our work constitutes a stepping stone towards the paradigm of self-correcting quantum information processing.

SELF-TRAPPING OF DISKOSEISMIC CORRUGATION MODES IN NEUTRON STAR SPACETIMES

Energy Technology Data Exchange (ETDEWEB)

Tsang, David [Center for Theory and Computation, Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Pappas, George [Department of Physics and Astronomy, The University of Mississippi, University, MS 38677 (United States)

2016-02-10

We examine the effects of higher-order multipole contributions of rotating neutron star (NS) spacetimes on the propagation of corrugation (c-)modes within a thin accretion disk. We find that the Lense–Thirring precession frequency, which determines the propagation region of the low-frequency fundamental corrugation modes, can experience a turnover allowing for c-modes to become self-trapped for sufficiently high dimensionless spin j and quadrupole rotational deformability α. If such self-trapping c-modes can be detected, e.g., through phase-resolved spectroscopy of the iron line for a high-spin low-mass accreting neutron star, this could potentially constrain the spin-induced NS quadrupole and the NS equation of state.

Self-Trapping of Diskoseismic Corrugation Modes in Neutron Star Spacetimes

Science.gov (United States)

Tsang, David; Pappas, George

2016-02-01

We examine the effects of higher-order multipole contributions of rotating neutron star (NS) spacetimes on the propagation of corrugation (c-)modes within a thin accretion disk. We find that the Lense-Thirring precession frequency, which determines the propagation region of the low-frequency fundamental corrugation modes, can experience a turnover allowing for c-modes to become self-trapped for sufficiently high dimensionless spin j and quadrupole rotational deformability α. If such self-trapping c-modes can be detected, e.g., through phase-resolved spectroscopy of the iron line for a high-spin low-mass accreting neutron star, this could potentially constrain the spin-induced NS quadrupole and the NS equation of state.

Study of the irreversible trapping of dihydrogen with the use of a MnO2/Ag2O mixture

International Nuclear Information System (INIS)

Galliez, K.

2012-01-01

The hydrogen risk generated by radiolysis of organic compounds during a nuclear waste transport is a major issue. The use of irreversible getters is considered to limit this risk. The aim of this work is to study one of these getters, MnO 2 /Ag 2 O, in order to better understand the trapping phenomenon and to ensure its reliability. Initially several parameters affecting the trapping kinetics were studied. It has been shown that among all MnO 2 allotropic phases, the nsutite has the best trapping kinetics. Moreover, specific surface area and defect amount in MnO 2 can enhance trapping performances. Ag 2 O weight percentage (acting as promotor) has been determined at 13% to have the best trapping kinetics. Chemisorption of H 2 , which is required for its application, has been shown by using several characterization techniques such as magnetometry, infrared spectroscopy and electronic energy loss spectroscopy. The trapping irreversibility and the regeneration of the getter have been demonstrated respectively under nitrogen or air at 150 C. Finally, proton insertion mechanism in MnO 2 has been elucidated by pairs distribution function analysis through the development of a model to simulate the complex structure of MnO 2 . It has been shown that Ag 2 O is turned into Ag 2 CO 3 during the preparation of the getter under water, which has never been demonstrated. (author) [fr

Impedance spectroscopy of organic magnetoresistance devices—Effect of interface disorder

International Nuclear Information System (INIS)

Fayolle, M.; Yamaguchi, M.; Ohto, T.; Tada, H.

2015-01-01

Organic magnetoresistance (OMAR) can be caused by either single carrier (bipolaron) or double carriers (electron-hole)-based mechanisms. In order to consider applications for OMAR, it is important to control the mechanism present in the device. In this paper, we report the effect of traps on OMAR resulting of disorder at the interface between the organic active layer with the hole injection layer [poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate): PEDOT:PSS]. It has been found that while the single carriers OMAR is enhanced by the presence of traps, the double carriers OMAR is totally removed in a sample with a high interface trap density. The reasons for these results are discussed based on the impedance spectroscopy measurements. First, the mechanism (single or double carriers) responsible of the OMAR was determined with the support of the capacitance measurement. Then, the influence of traps was discussed with the Nyquist diagrams and phase angle-frequency plots of the samples. The results suggested that with a rough interface and thus high disorder, the presence of traps enhanced the bipolaron formation. Traps also acted as recombination centers for electron-hole pairs, which prevented the double carriers OMAR in devices with a rough interface. On the other hand, with a low trap density, i.e., with a smooth surface, the single carrier OMAR decreased, and double carriers OMAR appeared. The sign of the OMAR could then be controlled by simply sweeping the bias voltage. This work demonstrated that the roughness at the interface is important for controlling OMAR and its reproducibility, and that the combination of OMAR measurement and impedance spectroscopy is helpful for clarifying the processes at the interface

Multiple-trapping in pentacene field-effect transistors with a nanoparticles self-assembled monolayer

Directory of Open Access Journals (Sweden)

Keanchuan Lee

2012-06-01

Full Text Available A silver nanoparticles self-assembled monolayer (SAM was incorporated in pentacene field-effect transistor and its effects on the carrier injection and transport were investigated using the current-voltage (I − V and impedance spectroscopy (IS measurements. The I − V results showed that there was a significant negative shift of the threshold voltage, indicating the hole trapping inside the devices with about two orders higher in the contact resistance and an order lower in the effective mobility when a SAM was introduced. The IS measurements with the simulation using a Maxwell-Wagner equivalent circuit model revealed the existence of multiple trapping states for the devices with NPs, while the devices without NPs exhibited only a single trap state.

High-precision x-ray spectroscopy of highly charged ions with microcalorimeters

International Nuclear Information System (INIS)

Kraft-Bermuth, S; Andrianov, V; Bleile, A; Echler, A; Egelhof, P; Grabitz, P; Ilieva, S; Kiselev, O; Meier, J; Kilbourne, C; McCammon, D

2013-01-01

The precise determination of the energy of the Lyman α1 and α2 lines in hydrogen-like heavy ions provides a sensitive test of quantum electrodynamics in very strong Coulomb fields. To improve the experimental precision, the new detector concept of microcalorimeters is now exploited for such measurements. Such detectors consist of compensated-doped silicon thermistors and Pb or Sn absorbers to obtain high quantum efficiency in the energy range of 40–70 keV, where the Doppler-shifted Lyman lines are located. For the first time, a microcalorimeter was applied in an experiment to precisely determine the transition energy of the Lyman lines of lead ions at the experimental storage ring at GSI. The energy of the Ly α1 line E(Ly-α1, 207 Pb 81+ ) = (77937 ± 12 stat ± 25 syst ) eV agrees within error bars with theoretical predictions. To improve the experimental precision, a new detector array with more pixels and better energy resolution was equipped and successfully applied in an experiment to determine the Lyman-α lines of gold ions 197 Au 78+ . (paper)

Advances in Contactless Silicon Defect and Impurity Diagnostics Based on Lifetime Spectroscopy and Infrared Imaging

Directory of Open Access Journals (Sweden)

Jan Schmidt

2007-01-01

Full Text Available This paper gives a review of some recent developments in the field of contactless silicon wafer characterization techniques based on lifetime spectroscopy and infrared imaging. In the first part of the contribution, we outline the status of different lifetime spectroscopy approaches suitable for the identification of impurities in silicon and discuss—in more detail—the technique of temperature- and injection-dependent lifetime spectroscopy. The second part of the paper focuses on the application of infrared cameras to analyze spatial inhomogeneities in silicon wafers. By measuring the infrared signal absorbed or emitted from light-generated free excess carriers, high-resolution recombination lifetime mappings can be generated within seconds to minutes. In addition, mappings of non-recombination-active trapping centers can be deduced from injection-dependent infrared lifetime images. The trap density has been demonstrated to be an important additional parameter in the characterization and assessment of solar-grade multicrystalline silicon wafers, as areas of increased trap density tend to deteriorate during solar cell processing.

Mass sensors with mechanical traps for weighing single cells in different fluids.

Science.gov (United States)

Weng, Yaochung; Delgado, Francisco Feijó; Son, Sungmin; Burg, Thomas P; Wasserman, Steven C; Manalis, Scott R

2011-12-21

We present two methods by which single cells can be mechanically trapped and continuously monitored within the suspended microchannel resonator (SMR) mass sensor. Since the fluid surrounding the trapped cell can be quickly and completely replaced on demand, our methods are well suited for measuring changes in cell size and growth in response to drugs or other chemical stimuli. We validate our methods by measuring the density of single polystyrene beads and Saccharomyces cerevisiae yeast cells with a precision of approximately 10(-3) g cm(-3), and by monitoring the growth of single mouse lymphoblast cells before and after drug treatment.

Electron beam ion trap bi-annual report 1996/1997

International Nuclear Information System (INIS)

Schneider, D.

1999-01-01

polarization measurements on high-Z highly charged ions. Studies of the interaction of highly charged ions with solid surfaces and thin foil targets reveal new interaction phenomena. The measurements of high secondary ion sputter yields led to the development of a prototype electron/ion emission microscope, which allows simultaneous topographic and chemical composition analysis with high sensitivity and spatial resolution. The enabling technology to trap, confine, and cool hundreds of highly charged ions in a precision Penning trap has been established and first evidence for the formation of a strongly coupled highly charged ion plasma via a sympathetic laser/ion cooling scheme has been observed. The benefits to DOE programs for a continued long term EBIT program are evident. The program requires the application and development of state-of-the-art experimental techniques necessary for spectroscopy, ion confinement and manipulation with spin-off applications in other laboratory programs. Thus, it serves as an excellent training ground for young scientists who will later work on energy-related plasma research or similar areas. It promises new research results towards the growth of our understanding of basic physics phenomena in atomic, nuclear and plasma physics, such as solid phases, astrophysical plasma evolution, and quantum control. This research will also provide input for applications in areas like ion beam manipulation and control for materials research. The activities at EBIT have created great interest among scientists from other areas (e.g. biology and environmental sciences) with several new ideas and research directions emerging. External funding for the project has in part been provided by the DOE office of Basic Energy Science (Chemical Science Division) and by NASA

Fast antihydrogen beam spectroscopy

International Nuclear Information System (INIS)

Neumann, R.

1989-01-01

The motivation for production and precision spectroscopy of antihydrogen atoms is outlined. An experimental configuration is considered, concerning laser-microwave spectroscopy of a fast hydrogen beam with characteristics similar to those of an antihydrogen beam emanating from an antiproton-positron overlap region in an antiproton storage ring. In particular, a possible experiment for the measurement of the ground state hyperfine structure splitting is described. (orig.)

Biomolecular EPR spectroscopy

CERN Document Server

Hagen, Wilfred Raymond

2008-01-01

Comprehensive, Up-to-Date Coverage of Spectroscopy Theory and its Applications to Biological SystemsAlthough a multitude of books have been published about spectroscopy, most of them only occasionally refer to biological systems and the specific problems of biomolecular EPR (bioEPR). Biomolecular EPR Spectroscopy provides a practical introduction to bioEPR and demonstrates how this remarkable tool allows researchers to delve into the structural, functional, and analytical analysis of paramagnetic molecules found in the biochemistry of all species on the planet. A Must-Have Reference in an Intrinsically Multidisciplinary FieldThis authoritative reference seamlessly covers all important bioEPR applications, including low-spin and high-spin metalloproteins, spin traps and spin lables, interaction between active sites, and redox systems. It is loaded with practical tricks as well as do's and don'ts that are based on the author's 30 years of experience in the field. The book also comes with an unprecedented set of...

Precision Mass Measurement of Argon Isotopes

CERN Multimedia

Lunney, D

2002-01-01

% IS388\\\\ \\\\ A precision mass measurement of the neutron-deficient isotopes $^{32,33,34}$Ar is proposed. Mass values of these isotopes are of importance for: a) a stringent test of the Isobaric-Multiplet- Mass-Equation, b) a verification of the correctness of calculated charge-dependent corrections as used in super-allowed $\\beta$- decay studies aiming at a test of the CVC hypothesis, and c) the determination of the kinematics in electron-neutrino correlation experiments searching for scalar currents in weak interaction. The measurements will be carried out with the ISOLTRAP Penning trap mass spectrometer.

Physics at CERN's Antiproton Decelerator

CERN Document Server

Hori, M

2013-01-01

The Antiproton Decelerator of CERN began operation in 1999 to serve experiments for studies of CPT invariance by precision laser and microwave spectroscopy of antihydrogen ($\\bar{\\rm H}$) and antiprotonic helium ($\\bar{p}{\\rm He}^+$). The first 12 years of operation saw cold $\\bar{\\rm H}$ synthesized by overlapping clouds of positrons ($e^+$) and antiprotons ($\\bar{p}$) confined in magnetic Penning traps. Cold $\\bar{\\rm H}$ was also produced in collisions between Rydberg positronium atoms and $\\bar{p}$. Ground-state $\\bar{\\rm H}$ was later trapped for up to $\\sim 1000$ s in a magnetic bottle trap, and microwave transitions excited between its hyperfine levels. In the $\\bar{p}{\\rm He}^+$ atom, UV transitions were measured to a precision of (2.3-5) $\\times$ $10^{-9}$ by sub-Doppler two-photon laser spectroscopy. From this the antiproton-to-electron mass ratio was determined as $M_{\\bar{p}}/m_e=$1836.1526736(23), which agrees with the p value. Microwave spectroscopy of $\\bar{p}{\\rm He}^+$ yielded a measurement o...

Scent Lure Effect on Camera-Trap Based Leopard Density Estimates.

Directory of Open Access Journals (Sweden)

Alexander Richard Braczkowski

Full Text Available Density estimates for large carnivores derived from camera surveys often have wide confidence intervals due to low detection rates. Such estimates are of limited value to authorities, which require precise population estimates to inform conservation strategies. Using lures can potentially increase detection, improving the precision of estimates. However, by altering the spatio-temporal patterning of individuals across the camera array, lures may violate closure, a fundamental assumption of capture-recapture. Here, we test the effect of scent lures on the precision and veracity of density estimates derived from camera-trap surveys of a protected African leopard population. We undertook two surveys (a 'control' and 'treatment' survey on Phinda Game Reserve, South Africa. Survey design remained consistent except a scent lure was applied at camera-trap stations during the treatment survey. Lures did not affect the maximum movement distances (p = 0.96 or temporal activity of female (p = 0.12 or male leopards (p = 0.79, and the assumption of geographic closure was met for both surveys (p >0.05. The numbers of photographic captures were also similar for control and treatment surveys (p = 0.90. Accordingly, density estimates were comparable between surveys (although estimates derived using non-spatial methods (7.28-9.28 leopards/100km2 were considerably higher than estimates from spatially-explicit methods (3.40-3.65 leopards/100km2. The precision of estimates from the control and treatment surveys, were also comparable and this applied to both non-spatial and spatial methods of estimation. Our findings suggest that at least in the context of leopard research in productive habitats, the use of lures is not warranted.

Slopes To Prevent Trapping of Bubbles in Microfluidic Channels

Science.gov (United States)

Greer, Harold E.; Lee, Michael C.; Smith, J. Anthony; Willis, Peter A.

2010-01-01

The idea of designing a microfluidic channel to slope upward along the direction of flow of the liquid in the channel has been conceived to help prevent trapping of gas bubbles in the channel. In the original application that gave rise to this idea, the microfluidic channels are parts of micro-capillary electrophoresis (microCE) devices undergoing development for use on Mars in detecting compounds indicative of life. It is necessary to prevent trapping of gas bubbles in these devices because uninterrupted liquid pathways are essential for sustaining the electrical conduction and flows that are essential for CE. The idea is also applicable to microfluidic devices that may be developed for similar terrestrial microCE biotechnological applications or other terrestrial applications in which trapping of bubbles in microfluidic channels cannot be tolerated. A typical microCE device in the original application includes, among other things, multiple layers of borosilicate float glass wafers. Microfluidic channels are formed in the wafers, typically by use of wet chemical etching. The figure presents a simplified cross section of part of such a device in which the CE channel is formed in the lowermost wafer (denoted the channel wafer) and, according to the present innovation, slopes upward into a via hole in another wafer (denoted the manifold wafer) lying immediately above the channel wafer. Another feature of the present innovation is that the via hole in the manifold wafer is made to taper to a wider opening at the top to further reduce the tendency to trap bubbles. At the time of reporting the information for this article, an effort to identify an optimum technique for forming the slope and the taper was in progress. Of the techniques considered thus far, the one considered to be most promising is precision milling by use of femtosecond laser pulses. Other similar techniques that may work equally well are precision milling using a focused ion beam, or a small diamond

Precision mass measurements of neutron-rich Co isotopes beyond N =40

Science.gov (United States)

Izzo, C.; Bollen, G.; Brodeur, M.; Eibach, M.; Gulyuz, K.; Holt, J. D.; Kelly, J. M.; Redshaw, M.; Ringle, R.; Sandler, R.; Schwarz, S.; Stroberg, S. R.; Sumithrarachchi, C. S.; Valverde, A. A.; Villari, A. C. C.

2018-01-01

The region near Z =28 and N =40 is a subject of great interest for nuclear structure studies due to spectroscopic signatures in 68Ni suggesting a subshell closure at N =40 . Trends in nuclear masses and their derivatives provide a complementary approach to shell structure investigations via separation energies. Penning trap mass spectrometry has provided precise measurements for a number of nuclei in this region; however, a complete picture of the mass surfaces has so far been limited by the large uncertainty remaining for nuclei with N >40 along the iron (Z =26 ) and cobalt (Z =27 ) chains because these species are not available from traditional isotope separator online rare isotope facilities. The Low-Energy Beam and Ion Trap Facility at the National Superconducting Cyclotron Laboratory is the first and only Penning trap mass spectrometer coupled to a fragmentation facility and therefore presents the unique opportunity to perform precise mass measurements of these elusive isotopes. Here we present the first Penning trap measurements of Co,6968, carried out at this facility. Some ambiguity remains as to whether the measured values are ground-state or isomeric-state masses. A detailed discussion is presented to evaluate this question and to motivate future work. In addition, we perform ab initio calculations of ground-state and two-neutron separation energies of cobalt isotopes with the valence-space in-medium similarity renormalization group approach based on a particular set of two- and three-nucleon forces that predict saturation in infinite matter. We discuss the importance of these measurements and calculations for understanding the evolution of nuclear structure near 68Ni.

Investigations of the ground-state hyperfine atomic structure and beta decay measurement prospects of ²¹Na with improved laser trapping techniques

Energy Technology Data Exchange (ETDEWEB)

Rowe, Mary Anderson [Univ. of California, Berkeley, CA (United States)

1999-05-01

This thesis describes an experiment in which a neutral atom laser trap loaded with radioactive ²¹Na was improved and then used for measurements. The sodium isotope (half-life=22 sec) is produced on line at the 88 in. cyclotron at Lawrence Berkeley National Laboratory. The author developed an effective magnesium oxide target system which is crucial to deliver a substantive beam of ²¹Na to the experiment. Efficient manipulation of the ²¹Na beam with lasers allowed 30,000 atoms to be contained in a magneto-optical trap. Using the cold trapped atoms, the author measured to high precision the hyperfine splitting of the atomic ground state of ²¹Na. She measured the 3S_1/2(F=1,m=0)-3S_1/2(F=2,m=0) atomic level splitting of ²¹Na to be 1,906,471,870±200 Hz. Additionally, she achieved initial detection of beta decay from the trap and evaluated the prospects of precision beta decay correlation studies with trapped atoms.

Utilization of the ion traps by SPIRAL

International Nuclear Information System (INIS)

Le Brun, C.; Lienard, E.; Mauger, F.; Tamain, B.

1997-01-01

An ion trap is a device capable of confine particles, ions or atoms in a well-controlled environment isolated from any exterior perturbations. There are different traps. They are utilized to collect or stock ions, to cool them after in order to subject them to high precision measurement of masses, magnetic moments, hyperfine properties, beta decay properties, etc. Some dozen of traps are currently used all over the world to study stable or radioactive ions.. SPIRAL has been designed and built to produce radioactive ions starting from various heavy ion beams. SPIRAL has the advantage that the projectile parameters, the target and the energy can be chosen to optimize the production in various regions of the nuclear chart. Also, in SPIRAL it is possible to extract more rapidly the radioactive ions formed in the targets. In addition, in SPIRAL the multicharged ion production in a ECR source is possible. The utilization of multicharged ions is indeed very useful for fast mass measurements or for the study of the interaction between the nucleus and the electronic cloud. Finally, utilization of a ion trap on SPIRAL can be designed first at the level of production target by installing a low energy output line. Than, the trap system could be up-graded and brought to its full utilization behind of the recoil spectrometer. It must be capable of selecting and slowing down the ions produced in the reactions (fusion transfer, very inelastic collisions, etc.) induced by the radioactive ions accelerated in CIME. At present, the collaboration is debating on the most favored subject to study and the most suited experimental setups. The following subjects were selected: ion capture, purification and manipulation; isomers (separation and utilization); mass measurements; hyperfine interactions; lifetimes, nuclear electric cloud; β decays; study of the N = Z nuclei close to the proton drip line; physical and chemical properties of transuranium systems

Deep traps at GaAs/GaAs interface grown by MBE-interruption growth technique

International Nuclear Information System (INIS)

Kaniewska, M.; Engstroem, O.

2007-01-01

Electron trapping centers at the GaAs/GaAs interface grown by molecular beam epitaxy (MBE)-interruption growth technique have been studied by capacitance versus voltage (C-V) measurements and deep level transient spectroscopy (DLTS). Two main electron traps have been revealed with activation energies at 0.16 eV and 0.52 eV from the conduction band. Inhomogeneous spatial distributions of the traps, obtained by DLTS profiling, indicate that they are agglomerated at the interrupted interface on a concentration level of (2-3) x 10 15 cm -3 at their maximum. Their behaviour is typical of acceptor-like traps when investigating by C-V profiling as a function of temperature. Based on a comparison made with electron traps in MBE-GaAs as well as with the traps in InAs/GaAs quantum dot/quantum well (QD/QW) structures, we conclude they are the well-known EL10 and EL4 defects, respectively, and their concentrations are growth condition dependent. They may be point defect-impurity complexes. Their presence may cause interpretation and application problems of the low-dimensional InAs/GaAs structures

Deep traps at GaAs/GaAs interface grown by MBE-interruption growth technique

Energy Technology Data Exchange (ETDEWEB)

Kaniewska, M. [Department of Analysis of Semicoductor Nanostructures, Institute of Electron Technology, Al. Lotnikow 32/46, 02-668 Warsaw (Poland)], E-mail: kaniew@ite.waw.pl; Engstroem, O. [Department of Microtechnology and Nanoscience, Chalmers University of Technology, SE-412 96 Goeteborg (Sweden)

2007-09-15

Electron trapping centers at the GaAs/GaAs interface grown by molecular beam epitaxy (MBE)-interruption growth technique have been studied by capacitance versus voltage (C-V) measurements and deep level transient spectroscopy (DLTS). Two main electron traps have been revealed with activation energies at 0.16 eV and 0.52 eV from the conduction band. Inhomogeneous spatial distributions of the traps, obtained by DLTS profiling, indicate that they are agglomerated at the interrupted interface on a concentration level of (2-3) x 10{sup 15} cm{sup -3} at their maximum. Their behaviour is typical of acceptor-like traps when investigating by C-V profiling as a function of temperature. Based on a comparison made with electron traps in MBE-GaAs as well as with the traps in InAs/GaAs quantum dot/quantum well (QD/QW) structures, we conclude they are the well-known EL10 and EL4 defects, respectively, and their concentrations are growth condition dependent. They may be point defect-impurity complexes. Their presence may cause interpretation and application problems of the low-dimensional InAs/GaAs structures.

In-Source Laser Spectroscopy with the Laser Ion Source and Trap: First Direct Study of the Ground-State Properties of ^{217,219}Po

Directory of Open Access Journals (Sweden)

D. A. Fink

2015-02-01

Full Text Available A Laser Ion Source and Trap (LIST for a thick-target, isotope-separation on-line facility has been implemented at CERN ISOLDE for the production of pure, laser-ionized, radioactive ion beams. It offers two modes of operation, either as an ion guide, which performs similarly to the standard ISOLDE resonance ionization laser ion source (RILIS, or as a more selective ion source, where surface-ionized ions from the hot ion-source cavity are repelled by an electrode, while laser ionization is done within a radio-frequency quadrupole ion guide. The first physics application of the LIST enables the suppression of francium contamination in ion beams of neutron-rich polonium isotopes at ISOLDE by more than 1000 with a reduction in laser-ionization efficiency of only 20. Resonance ionization spectroscopy is performed directly inside the LIST device, allowing the study of the hyperfine structure and isotope shift of ^{217}Po for the first time. Nuclear decay spectroscopy of ^{219}Po is performed for the first time, revealing its half-life, α-to-β-decay branching ratio, and α-particle energy. This experiment demonstrates the applicability of the LIST at radioactive ion-beam facilities for the production and study of pure beams of exotic isotopes.

C60 as an Atom Trap to Capture Co Adatoms

DEFF Research Database (Denmark)

Yang, Peng; Li, Dongzhe; Repain, Vincent

2015-01-01

C60 molecules were used to trap Co adatoms and clusters on a Au(111) surface using atomic/molecular manipulation with a scanning tunneling microscope. Two manipulation pathways (successive integration of single Co atoms in one molecule or direct integration of a Co cluster) were found...... to efficiently allow the formation of complexes mixing a C60 molecule with Co atoms. Scanning tunneling spectroscopy reveals the robustness of the pi states of C60 that are preserved after Co trapping. Scanning tunneling microscopy images and density functional theory calculations reveal that dissociated Co...... clusters of up to nine atoms can be formed at the molecule-substrate interface. These results open new perspectives in the interactions between metal adatoms and molecules, for applications in metal-organic devices...

Hyperfine structure and isotope-shift measurements of short-lived elements by laser spectroscopy. Progress report, January 1, 1980-August 31, 1981

International Nuclear Information System (INIS)

Schuessler, H.A.

1981-09-01

Work is reported on numerical studies of the trapping of continuous ion beams injected into various ion traps, numerical studies of the trapping of the pulsed ion beams injected into a radio frequency ion trap, construction of a plasma ion source and a radio frequency ion trap, development of a laser system for the spectroscopy of stored ions, and experiments with quartz cells at high temperatures

Majority- and minority-carrier deep level traps in proton-irradiated n+/p-InGaP space solar cells

International Nuclear Information System (INIS)

Dharmarasu, Nethaji; Yamaguchi, Masafumi; Bourgoin, Jacques C.; Takamoto, Tatsuya; Ohshima, Takeshi; Itoh, Hisayoshi; Imaizumi, Mitsuru; Matsuda, Sumio

2002-01-01

We report the properties of observed defects in n + /p-InGaP solar cells created by irradiation of protons of different energies. Three majority (hole) and a minority-carrier traps, labeled respectively as HP1 (E v +0.90±0.05 eV), HP2 (E v +0.73±0.05 eV), H2 (E v +0.55 eV), and EP1 (E c -0.54 eV), were identified using deep level transient spectroscopy. All majority-carrier traps were found to act as recombination centers. While the H2 trap present in the proton-irradiated p-InGaP was found to anneal out by minority-carrier injection, the other traps were not

Experimental and computational study of the injection of antiprotons into a positron plasma for antihydrogen production

DEFF Research Database (Denmark)

Amole, C.; Ashkezari, M.D.; Baquero-Ruiz, M.

2013-01-01

One of the goals of synthesizing and trapping antihydrogen is to study the validity of charge-parity-time symmetry through precision spectroscopy on the anti-atoms, but the trapping yield achieved in recent experiments must be significantly improved before this can be realized. Antihydrogen atoms...... and upcoming antihydrogen experiments, and the latter scheme is seen to offer significant improvement in trapping yield as the number of available antiprotons increases....

Sideband cooling and coherent dynamics in a microchip multi-segmented ion trap

Energy Technology Data Exchange (ETDEWEB)

Schulz, Stephan A; Poschinger, Ulrich; Ziesel, Frank; Schmidt-Kaler, Ferdinand [Universitaet Ulm, Institut fuer Quanteninformationsverarbeitung, Albert-Einstein-Allee 11, D-89069 Ulm (Germany)], E-mail: stephan.schulz@uni-ulm.de

2008-04-15

Miniaturized ion trap arrays with many trap segments present a promising architecture for scalable quantum information processing. The miniaturization of segmented linear Paul traps allows partitioning the microtrap into different storage and processing zones. The individual position control of many ions-each of them carrying qubit information in its long-lived electronic levels-by the external trap control voltages is important for the implementation of next generation large-scale quantum algorithms. We present a novel scalable microchip multi-segmented ion trap with two different adjacent zones, one for the storage and another dedicated to the processing of quantum information using single ions and linear ion crystals. A pair of radio-frequency-driven electrodes and 62 independently controlled dc electrodes allows shuttling of single ions or linear ion crystals with numerically designed axial potentials at axial and radial trap frequencies of a few megahertz. We characterize and optimize the microtrap using sideband spectroscopy on the narrow S{sub 1/2}{r_reversible}D{sub 5/2} qubit transition of the {sup 40}Ca{sup +} ion, and demonstrate coherent single-qubit Rabi rotations and optical cooling methods. We determine the heating rate using sideband cooling measurements to the vibrational ground state, which is necessary for subsequent two-qubit quantum logic operations. The applicability for scalable quantum information processing is proved.

The control mechanism of surface traps on surface charge behavior in alumina-filled epoxy composites

International Nuclear Information System (INIS)

Li, Chuanyang; Hu, Jun; Lin, Chuanjie; He, Jinliang

2016-01-01

To investigate the role surface traps play in the charge injection and transfer behavior of alumina-filled epoxy composites, surface traps with different trap levels are introduced by different surface modification methods which include dielectric barrier discharges plasma, direct fluorination, and Cr 2 O 3 coating. The resulting surface physicochemical characteristics of experimental samples were observed using atomic force microscopy, scanning electron microscopy and fourier transform infrared spectroscopy. The surface potential under dc voltage was detected and the trap level distribution was measured. The results suggest that the surface morphology of the experimental samples differs dramatically after treatment with different surface modification methods. Different surface trap distributions directly determine the charge injection and transfer property along the surface. Shallow traps with trap level of 1.03–1.11 eV and 1.06–1.13 eV introduced by plasma and fluorination modifications are conducive for charge transport along the insulating surface, and the surface potential can be modified, producing a smoother potential curve. The Cr 2 O 3 coating can introduce a large number of deep traps with energy levels ranging from 1.09 to 1.15 eV. These can prevent charge injection through the reversed electric field formed by intensive trapped charges in the Cr 2 O 3 coatings. (paper)

Precision spectroscopy on hydrogen and deuterium. Test of the bound-state quantum electrodynamics

International Nuclear Information System (INIS)

Fendel, P.

2005-06-01

An optical measurement of the hyperfine splitting of the 2s state in deuterium performed for the first time and the description of the arrangement for the measurement of the 1s-3s frequency in hydrogen by excitation with a frequency combexpect the reader of this thesis. Both experiments have the goal to test the bound-state quantum electrodynamics (QED) with high precision. The measurement of the hyperfine splitting serves thereby for the improvement of the accuracy of the so called D 21 =8E HFS (2s)-E HFS (1s) difference. Because D 21 is far-reachingly independent on the nuclear structure in spite of not accurately known proton charge radii QED can be tested on a level of 10 -7 . In the framework of the thesis present here the error of this quantity was reduced by a factor of three. The result for the 2s hyperfine splitting is: f D HFS =40924454(7) Hz. By a new kind of the data acquisition furthermore many systematic errors, especially the nonlinear drift of the reference resonator, could be reduced in comparison to a similar measurement on hydrogen. The second part of the thesis describes the efforts which were and will be taken in order to test QED by means of their perdiction of the 1s Lamb shift. For this the frequency of the 1s-3s transition in hydrogen shall be measured absolutely for the first time. A further novum is that for this a frequency-quadrupled mode-coupled laser shall be come into operation. Especially the construction and the stabilization of a ps laser, the construction of two frequency-doubling stages, the arrangement for the measurement of the absolute frequency of the spectroscopy laser, the alteration of the existing 1s-2s vacuum system, and the development of the measurement software is described. Additionally in this thesis the theory of the two-photon frequency-comb spectroscopy is further developed. Concrete expressions for the expected line shape and the influence of the chirp on the excitation rate are presented

Design of guanidinium ionic liquid based microwave-assisted extraction for the efficient extraction of Praeruptorin A from Radix peucedani.

Science.gov (United States)

Ding, Xueqin; Li, Li; Wang, Yuzhi; Chen, Jing; Huang, Yanhua; Xu, Kaijia

2014-12-01

A series of novel tetramethylguanidinium ionic liquids and hexaalkylguanidinium ionic liquids have been synthesized based on 1,1,3,3-tetramethylguanidine. The structures of the ionic liquids were confirmed by (1)H NMR spectroscopy and mass spectrometry. A green guanidinium ionic liquid based microwave-assisted extraction method has been developed with these guanidinium ionic liquids for the effective extraction of Praeruptorin A from Radix peucedani. After extraction, reversed-phase high-performance liquid chromatography with UV detection was employed for the analysis of Praeruptorin A. Several significant operating parameters were systematically optimized by single-factor and L9 (3(4)) orthogonal array experiments. The amount of Praeruptorin A extracted by [1,1,3,3-tetramethylguanidine]CH2CH(OH)COOH is the highest, reaching 11.05 ± 0.13 mg/g. Guanidinium ionic liquid based microwave-assisted extraction presents unique advantages in Praeruptorin A extraction compared with guanidinium ionic liquid based maceration extraction, guanidinium ionic liquid based heat reflux extraction and guanidinium ionic liquid based ultrasound-assisted extraction. The precision, stability, and repeatability of the process were investigated. The mechanisms of guanidinium ionic liquid based microwave-assisted extraction were researched by scanning electron microscopy and IR spectroscopy. All the results show that guanidinium ionic liquid based microwave-assisted extraction has a huge potential in the extraction of bioactive compounds from complex samples. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effects of oxide traps, interface traps, and ''border traps'' on metal-oxide-semiconductor devices

International Nuclear Information System (INIS)

Fleetwood, D.M.; Winokur, P.S.; Reber, R.A. Jr.; Meisenheimer, T.L.; Schwank, J.R.; Shaneyfelt, M.R.; Riewe, L.C.

1993-01-01

We have identified several features of the 1/f noise and radiation response of metal-oxide-semiconductor (MOS) devices that are difficult to explain with standard defect models. To address this issue, and in response to ambiguities in the literature, we have developed a revised nomenclature for defects in MOS devices that clearly distinguishes the language used to describe the physical location of defects from that used to describe their electrical response. In this nomenclature, ''oxide traps'' are simply defects in the SiO 2 layer of the MOS structure, and ''interface traps'' are defects at the Si/SiO 2 interface. Nothing is presumed about how either type of defect communicates with the underlying Si. Electrically, ''fixed states'' are defined as trap levels that do not communicate with the Si on the time scale of the measurements, but ''switching states'' can exchange charge with the Si. Fixed states presumably are oxide traps in most types of measurements, but switching states can either be interface traps or near-interfacial oxide traps that can communicate with the Si, i.e., ''border traps'' [D. M. Fleetwood, IEEE Trans. Nucl. Sci. NS-39, 269 (1992)]. The effective density of border traps depends on the time scale and bias conditions of the measurements. We show the revised nomenclature can provide focus to discussions of the buildup and annealing of radiation-induced charge in non-radiation-hardened MOS transistors, and to changes in the 1/f noise of MOS devices through irradiation and elevated-temperature annealing

FROM PERSONALIZED TO PRECISION MEDICINE

Directory of Open Access Journals (Sweden)

K. V. Raskina

2017-01-01

Full Text Available The need to maintain a high quality of life against a backdrop of its inevitably increasing duration is one of the main problems of modern health care. The concept of "right drug to the right patient at the right time", which at first was bearing the name "personalized", is currently unanimously approved by international scientific community as "precision medicine". Precision medicine takes all the individual characteristics into account: genes diversity, environment, lifestyles, and even bacterial microflora and also involves the use of the latest technological developments, which serves to ensure that each patient gets assistance fitting his state best. In the United States, Canada and France national precision medicine programs have already been submitted and implemented. The aim of this review is to describe the dynamic integration of precision medicine methods into routine medical practice and life of modern society. The new paradigm prospects description are complemented by figures, proving the already achieved success in the application of precise methods for example, the targeted therapy of cancer. All in all, the presence of real-life examples, proving the regularity of transition to a new paradigm, and a wide range  of technical and diagnostic capabilities available and constantly evolving make the all-round transition to precision medicine almost inevitable.

Memory properties and charge effect study in Si nanocrystals by scanning capacitance microscopy and spectroscopy

Directory of Open Access Journals (Sweden)

Bassani Franck

2011-01-01

Full Text Available Abstract In this letter, isolated Si nanocrystal has been formed by dewetting process with a thin silicon dioxide layer on top. Scanning capacitance microscopy and spectroscopy were used to study the memory properties and charge effect in the Si nanocrystal in ambient temperature. The retention time of trapped charges injected by different direct current (DC bias were evaluated and compared. By ramp process, strong hysteresis window was observed. The DC spectra curve shift direction and distance was observed differently for quantitative measurements. Holes or electrons can be separately injected into these Si-ncs and the capacitance changes caused by these trapped charges can be easily detected by scanning capacitance microscopy/spectroscopy at the nanometer scale. This study is very useful for nanocrystal charge trap memory application.

Spatial capture–recapture with partial identity: An application to camera traps

Science.gov (United States)

Augustine, Ben C.; Royle, J. Andrew; Kelly, Marcella J.; Satter, Christopher B.; Alonso, Robert S.; Boydston, Erin E.; Crooks, Kevin R.

2018-01-01

Camera trapping surveys frequently capture individuals whose identity is only known from a single flank. The most widely used methods for incorporating these partial identity individuals into density analyses discard some of the partial identity capture histories, reducing precision, and, while not previously recognized, introducing bias. Here, we present the spatial partial identity model (SPIM), which uses the spatial location where partial identity samples are captured to probabilistically resolve their complete identities, allowing all partial identity samples to be used in the analysis. We show that the SPIM outperforms other analytical alternatives. We then apply the SPIM to an ocelot data set collected on a trapping array with double-camera stations and a bobcat data set collected on a trapping array with single-camera stations. The SPIM improves inference in both cases and, in the ocelot example, individual sex is determined from photographs used to further resolve partial identities—one of which is resolved to near certainty. The SPIM opens the door for the investigation of trapping designs that deviate from the standard two camera design, the combination of other data types between which identities cannot be deterministically linked, and can be extended to the problem of partial genotypes.

Feasibility study of performing high precision gamma spectroscopy of {lambda}{lambda} hypernuclei in the anti PANDA experiment

Energy Technology Data Exchange (ETDEWEB)

Sanchez-Lorente, Alicia

2010-09-30

Hypernuclear research will be one of the main topics addressed by the anti PANDA experiment at the planned Facility for Antiproton and Ion Research anti FAIR. Thanks to the use of stored anti p beams, copious production of double {lambda} hypernuclei is expected at the anti PANDA experiment, which will enable high precision {gamma} spectroscopy of such nuclei for the first time. At anti PANDA excited states of {xi}{sup -} hypernuclei will be used as a basis for the formation of double {lambda} hypernuclei. For their detection, a devoted hypernuclear detector setup is planned. This setup consists of a primary nuclear target for the production of {xi}{sup -}+ anti {xi} pairs, a secondary active target for the hypernuclei formation and the identification of associated decay products and a germanium array detector to perform {gamma} spectroscopy. In the present work, the feasibility of performing high precision {gamma} spectroscopy of double {lambda} hypernuclei at the anti PANDA experiment has been studied by means of a Monte Carlo simulation. For this issue, the designing and simulation of the devoted detector setup as well as of the mechanism to produce double {lambda} hypernuclei have been optimized together with the performance of the whole system. In addition, the production yields of double hypernuclei in excitedparticle stable states have been evaluated within a statistical decay model. A strategy for the unique assignment of various newly observed {gamma}-transitions to specific double hypernuclei has been successfully implemented by combining the predicted energy spectra of each target with the measurement of two pion momenta from the subsequent weak decays of a double hypernucleus. Indeed, based on these Monte Carlo simulation, the analysis of the statistical decay of {sup 13}{sub {lambda}}{sub {lambda}}B has been performed. As result, three {gamma}-transitions associated to the double hypernuclei {sup 11}{sub {lambda}}{sub {lambda}}Be and to the single

Multivariate Calibration and Model Integrity for Wood Chemistry Using Fourier Transform Infrared Spectroscopy

Directory of Open Access Journals (Sweden)

Chengfeng Zhou

2015-01-01

Full Text Available This research addressed a rapid method to monitor hardwood chemical composition by applying Fourier transform infrared (FT-IR spectroscopy, with particular interest in model performance for interpretation and prediction. Partial least squares (PLS and principal components regression (PCR were chosen as the primary models for comparison. Standard laboratory chemistry methods were employed on a mixed genus/species hardwood sample set to collect the original data. PLS was found to provide better predictive capability while PCR exhibited a more precise estimate of loading peaks and suggests that PCR is better for model interpretation of key underlying functional groups. Specifically, when PCR was utilized, an error in peak loading of ±15 cm−1 from the true mean was quantified. Application of the first derivative appeared to assist in improving both PCR and PLS loading precision. Research results identified the wavenumbers important in the prediction of extractives, lignin, cellulose, and hemicellulose and further demonstrated the utility in FT-IR for rapid monitoring of wood chemistry.

Paul Trapping of Radioactive 6He+ Ions and Direct Observation of Their β Decay

International Nuclear Information System (INIS)

Flechard, X.; Lienard, E.; Mery, A.; Rodriguez, D.; Ban, G.; Durand, D.; Duval, F.; Herbane, M.; Labalme, M.; Mauger, F.; Naviliat-Cuncic, O.; Velten, Ph.; Thomas, J. C.

2008-01-01

We demonstrate that abundant quantities of short-lived β unstable ions can be trapped in a novel transparent Paul trap and that their decay products can directly be detected in coincidence. Low energy 6 He + (807 ms half-life) ions were extracted from the SPIRAL source at GANIL, then decelerated, cooled, and bunched by means of the buffer gas cooling technique. More than 10 8 ions have been stored over a measuring period of six days, and about 10 5 decay coincidences between the beta particles and the 6 Li ++ recoiling ions have been recorded. The technique can be extended to other short-lived species, opening new possibilities for trap assisted decay experiments

Experimental quantum simulations of many-body physics with trapped ions.

Science.gov (United States)

Schneider, Ch; Porras, Diego; Schaetz, Tobias

2012-02-01

Direct experimental access to some of the most intriguing quantum phenomena is not granted due to the lack of precise control of the relevant parameters in their naturally intricate environment. Their simulation on conventional computers is impossible, since quantum behaviour arising with superposition states or entanglement is not efficiently translatable into the classical language. However, one could gain deeper insight into complex quantum dynamics by experimentally simulating the quantum behaviour of interest in another quantum system, where the relevant parameters and interactions can be controlled and robust effects detected sufficiently well. Systems of trapped ions provide unique control of both the internal (electronic) and external (motional) degrees of freedom. The mutual Coulomb interaction between the ions allows for large interaction strengths at comparatively large mutual ion distances enabling individual control and readout. Systems of trapped ions therefore exhibit a prominent system in several physical disciplines, for example, quantum information processing or metrology. Here, we will give an overview of different trapping techniques of ions as well as implementations for coherent manipulation of their quantum states and discuss the related theoretical basics. We then report on the experimental and theoretical progress in simulating quantum many-body physics with trapped ions and present current approaches for scaling up to more ions and more-dimensional systems.

High temperature annealing of minority carrier traps in irradiated MOCVD n(+)p InP solar cell junctions

Science.gov (United States)

Messenger, S. R.; Walters, R. J.; Summers, G. P.

1993-01-01

Deep level transient spectroscopy was used to monitor thermal annealing of trapping centers in electron irradiated n(+)p InP junctions grown by metalorganic chemical vapor deposition, at temperatures ranging from 500 up to 650K. Special emphasis is given to the behavior of the minority carrier (electron) traps EA (0.24 eV), EC (0.12 eV), and ED (0.31 eV) which have received considerably less attention than the majority carrier (hole) traps H3, H4, and H5, although this work does extend the annealing behavior of the hole traps to higher temperatures than previously reported. It is found that H5 begins to anneal above 500K and is completely removed by 630K. The electron traps begin to anneal above 540K and are reduced to about half intensity by 630K. Although they each have slightly different annealing temperatures, EA, EC, and ED are all removed by 650K. A new hole trap called H3'(0.33 eV) grows as the other traps anneal and is the only trap remaining at 650K. This annealing behavior is much different than that reported for diffused junctions.

Shrew trap efficiency

DEFF Research Database (Denmark)

Gambalemoke, Mbalitini; Mukinzi, Itoka; Amundala, Drazo

2008-01-01

We investigated the efficiency of four trap types (pitfall, Sherman LFA, Victor snap and Museum Special snap traps) to capture shrews. This experiment was conducted in five inter-riverine forest blocks in the region of Kisangani. The total trapping effort was 6,300, 9,240, 5,280 and 5,460 trap......, our results indicate that pitfall traps are the most efficient for capturing shrews: not only do they have a higher efficiency (yield), but the taxonomic diversity of shrews is also higher when pitfall traps are used....

Trap characterization by photo-transferred thermoluminescence in MgO nanoparticles

Science.gov (United States)

Isik, M.; Gasanly, N. M.

2018-05-01

Shallow trapping centers in MgO nanoparticles were characterized using photo-transferred thermoluminescence (TL) measurements. Experiments were carried out in low temperature range of 10-280 K with constant heating rate. Shallow traps were filled with charge carriers firstly by irradiating the sample at room temperature using S90/Y90 source and then illuminating at 10 K using blue LED. TL glow curve exhibited one peak around 150 K. Curve fitting analyses showed that this peak is composed of two individual peaks with maximum temperatures of 149.0 and 155.3 K. The activation energies of corresponding trapping centers were revealed as 0.70 and 0.91 eV. The dominant mechanism for TL process was found as second order kinetics which represent that fast retrapping is effective transitions taking place within the band gap. Structural characterization of MgO nanoparticles were investigated using x-ray diffraction, scanning electron microscopy and Fourier transform infrared spectroscopy measurements. Analyses of experimental observations indicated that MgO nanoparticles show good crystallinity with particle size in nanometer scale.

Ambient-temperature trap/release of arsenic by dielectric barrier discharge and its application to ultratrace arsenic determination in surface water followed by atomic fluorescence spectrometry

Science.gov (United States)

A novel dielectric barrier discharge reactor (DBDR) was utilized to trap/release arsenic coupled to hydride generation atomic fluorescence spectrometry (HGAFS). On the DBD principle, the precise and accurate control of trap/release procedures was fulfilled at ambient temperature, and an analytical m...

Tests of CPT, Lorentz invariance and the WEP with antihydrogen

International Nuclear Information System (INIS)

Holzscheiter, M.H.

1999-01-01

Antihydrogen atoms, produced near rest, trapped in a magnetic well, and cooled to the lowest possible temperature (kinetic energy) could provide an extremely powerful tool for the search of violations of CPT and Lorentz invariance. Equally well, such a system could be used for searches of violations of the Weak Equivalence Principle (WEP) at high precision. The author describes his plans to form a significant number of cold, trapped antihydrogen atoms for comparative precision spectroscopy of hydrogen and antihydrogen and comment on possible first experiments

Overview of the Livermore electron beam ion trap project

International Nuclear Information System (INIS)

Beiersdorfer, P.; Behar, E.; Boyce, K.R.; Brown, G.V.; Chen, H.; Gendreau, K.C.; Graf, A.; Gu, M.-F.; Harris, C.L.; Kahn, S.M.; Kelley, R.L.; Lepson, J.K.; May, M.J.; Neill, P.A.; Pinnington, E.H.; Porter, F.S.; Smith, A.J.; Stahle, C.K.; Szymkowiak, A.E.; Tillotson, A.; Thorn, D.B.; Traebert, E.; Wargelin, B.J.

2003-01-01

The Livermore electron beam ion trap facility has recently been moved to a new location within LLNL, and new instrumentation was added, including a 32-pixel microcalorimeter. The move was accompanied by a shift of focus toward in situ measurements of highly charged ions, which continue with increased vigor. Overviews of the facility, which includes EBIT-I and SuperEBIT, and the research projects are given, including results from optical spectroscopy, QED, and X-ray line excitation measurements

Characterization of nitride hole lateral transport in a charge trap flash memory by using a random telegraph signal method

Science.gov (United States)

Liu, Yu-Heng; Jiang, Cheng-Min; Lin, Hsiao-Yi; Wang, Tahui; Tsai, Wen-Jer; Lu, Tao-Cheng; Chen, Kuang-Chao; Lu, Chih-Yuan

2017-07-01

We use a random telegraph signal method to investigate nitride trapped hole lateral transport in a charge trap flash memory. The concept of this method is to utilize an interface oxide trap and its associated random telegraph signal as an internal probe to detect a local channel potential change resulting from nitride charge lateral movement. We apply different voltages to the drain of a memory cell and vary a bake temperature in retention to study the electric field and temperature dependence of hole lateral movement in a nitride. Thermal energy absorption by trapped holes in lateral transport is characterized. Mechanisms of hole lateral transport in retention are investigated. From the measured and modeled results, we find that thermally assisted trap-to-band tunneling is a major trapped hole emission mechanism in nitride hole lateral transport.

Formation of hydrogen-related traps in electron-irradiated n-type silicon by wet chemical etching