Showing papers on "Time of flight published in 1970"
TL;DR: In this article, a target chamber for recoil-distance measurements of nuclear lifetimes is described, where the plunger can be set at 2 × 10 −4 inch from a target foil of 0.25 inch diameter without touching.
140 citations
TL;DR: In this paper, the output beam of a Ruby Giant Pulse Laser (30 nsec halfwidth, up to 100 MW peak power) was focussed onto the surface of aluminium and copper targets, which were cleaned by heating them to 500 degrees C at 10-7 torr.
Abstract: The output beam of a Ruby Giant Pulse Laser (30 nsec halfwidth, up to 100 MW peak power) was focussed onto the surface of aluminium and copper-targets, which were cleaned by heating them to 500 degrees C at 10-7 torr. The evaporated ions and electrons were detected at a distance of 170cm away from the target, after having passed some retarding grids. By a combination of time of flight- and retarding potential measurements the different charged ions could be separated and their energy distribution and intensity ratios were measured. his yields information simultaneously about the kinetic ion energies and the plasma electron temperature. It turns out, that the mean kinetic energy of the ions is proportional to their charge and about 100 times larger than their thermal energy. The experimental results and their interpretation in connection with the mechanisms of plasma generation and heating by laser light are discussed and compared with theoretical and experimental investigations of other authors.
75 citations
TL;DR: In this article, the authors compared the resolutions of time-of-flight (TOF) mass spectrometers with respect to their ability to compensate for initial ion velocities while operating in the space focusing mode.
Abstract: The resolutions of time‐of‐flight (TOF) mass spectrometers using multiple acceleration are compared with respect to their ability to compensate for initial ion velocities while operating in the space focusing mode. A theorem is proved which demonstrates that the Wiley‐McLaren two‐step TOF has the theoretical limit for energy resolution of a large class of spectrometers and has the practical limit for all other conventional TOF's which employ time independent fields. An alternate explanation is given for the increased resolution obtained by Studier.
47 citations
TL;DR: In this article, a zero-time detector of the secondary emission type in connection with a surface barrier semiconductor energy detector at the end of the flight path was used for mass identification of heavy ions from nuclear reactions in the mass-range 4≦ A ≦16.
44 citations
TL;DR: In this article, a new charged particle detector is described that is capable of registering the passage of very heavy ions (e.g. fission fragments) with only a few percent energy loss.
34 citations
TL;DR: In this paper, the times of flight of reactant and product ions from some low energy ion-neutral reactions are measured using a longitudinal double mass spectrometer system, which consists of a 2.54 cm 90 degree magnetic sector ion beam selector, a collision chamber and grid system, and a 46 cm quadrupole mass filter, together with a multichannel scaler, operated at dwell times of 50 nanosec per channel, that serves as a flight-time recorder.
28 citations
TL;DR: In this article, the absolute detection efficiency of neutron counters using NE102 plastic scintillator in the energy region from 5 to 40 MeV has been measured using a difference technique and compared with calculated values and with similar measurements made elsewhere.
23 citations
TL;DR: In this paper, the intensity and velocity distributions of thermal energy argon atoms scattered from silver /111/ face, using time of flight methods, were analyzed using time-of-flight methods.
Abstract: Intensity and velocity distributions of thermal energy argon atoms scattered from silver /111/ face, using time of flight methods
21 citations
TL;DR: In this paper, the metastable transitions of the molecular ions of trimethyl phosphate and 1,3-butadiene have been studied in a specially modified time of flight mass spectrometer, ionisation in the latter case being effected by photon impact.
13 citations
TL;DR: In this article, the measurement of the time of flight of ions in an inhomogeneous oscillatory electric field was used to spearate ions of different mass-to-charge ratios.
Abstract: The measurement of the time of flight of ions in an inhomogeneous oscillatory electric field is used to spearate ions of different mass‐to‐charge ratios. Analytical and experimental results are reported.
11 citations
TL;DR: In this paper, the authors present the results of a study of the X-ray Crystallography at Oak Ridge National Laboratory (ORNL) in the early 1960s and show that it is possible to obtain a state-of-the-art performance.
Abstract: BUSING, W. R., MARTIN, K. O. & LEVY, H. A. (1962). Report ORNL-TM-305, Oak Ridge National Laboratory, Tennessee. CHIBA, A., UEKI, T., ASHIDA, T., SASADA, Y. & KAKUDO, M. (1967). Acta Cryst. 22, 863. FREEMAN, H. C. (1967). Advanc. Protein Chem. 22, 257. GUHA, S., MAJUMDAR, S. K. & SAHA, N. N. (1969). Z. Kristallogr. 129, 84. International Tables for X-ray Crystallography (1960). Vol. III. Birmingham: Kynoch Press. PHILLIPS, D. C. (1954). Acta Cryst. 7, 746. PHILLIPS, D. C. (1956). Acta Cryst. 9, 819. RENNINGER, M. Z. (1937). Z. Kristallogr. 97, 107. TAURINS, A. (1950). Canad. J. Research, B28, 762.
TL;DR: The field ion microscope atom probe as mentioned in this paper makes possible the chemical identification of individual atoms field desorbed from a sharp metal tip by time of flight along a drift tube, and an instrument to control the rate at which desorption pulses are applied and to record the resulting data is described.
Abstract: The field ion microscope atom probe makes possible the chemical identification of individual atoms field desorbed from a sharp metal tip by time of flight along a drift tube. An instrument to control the rate at which desorption pulses are applied and to record the resulting data is described. Rates of a few hundred pulses per second are readily achieved, and the instrument can be programmed to terminate either after a present number of cycles or in response to the acquisition of the first piece of data. This latter mode of operation is particularly convenient for establishing the best field desorption conditions. Resolution of adjacent mass numbers depends on the time resolution of the instrument; the best time resolution achieved is 40 nsec, resulting in a mass resolution of about 1% for typical ion travel times.
TL;DR: In this article, the authors measured the mobility of ions in air using a time-of-flight method, using a rectangular cyclic voltage and eliminating harmonic peaks, which was shown to be more accurate than Bradbury's method.
Abstract: We have measured the mobility of ions in air. The method of measuring the mobility is a time‐of‐flight method. The time of flight of the ions is measured between two grids G1 and G2, as in Bradbury's method. We have improved the resolution of the apparatus, using a rectangular cyclic voltage, and we have eliminated harmonic peaks. Results with radioactive ions of ThC″ and ions created in air by the β rays of a tritium source are discussed.
TL;DR: In this article, the theory underlying the operation of a coincidence time-of-flight mass spectrometer is first developed and the construction of such an instrument is described, in which ionization is effected by a monoenergetic photon beam from the 584 A helium line.
TL;DR: In this article, a retarding potential device and a second gas inlet on the drift tube of a time-of-flight mass spectrometer were used to study ion-molecule reactions.
TL;DR: The time-of-flight facility used for the measurement of neutron spectra from (p,n) reactions in conjunction with the Rutherford Laboratory 50 MeV proton linear accelerator is described.
TL;DR: In this paper, the authors present a facility for making charge state identification of spectral lines using a technique which is compatible with the geometry employed for mean life measurements, where a set of parallel electric field plates can be raised in the observation chamber to beam level through vacuum feed-throughs and a transverse electric field applied.
TL;DR: In this article, a six-foot detector, covering an angular range of 17° at a distance of 6 m, has been developed, which has a time resolution in the range of 1 of 2 ns for an electronic threshold equivalent to 1.2 MeV neutrons.
TL;DR: In this paper, a general expression for total ion flight time is derived for a spectrometer having four concentric electrodes which bound two accelerating regions and a drift region, and it is shown that cylindrical geometry gives a higher order of space-time focusing than is possible with a conventional linear instrument having similarly spaced planar electrodes.
TL;DR: In this article, two methods for the measurement of the drift velocity of ions in liquids are described in detail, and the dc voltage applied across the drift length and the time or delays involved in the methods can be measured with an accuracy better than 0.1%.
Abstract: Two methods for the measurement of the drift velocity of ions in liquids are described in detail. Both the dc voltage applied across the drift length, and the time or delays involved in the methods can be measured with an accuracy better than 0.1%. Moreover the time of flight is deduced with good accuracy from an extrapolation of a linear plot of the ionic current as a function of time. As a result, drift velocity or mobility measurements with an accuracy of 1% or better can be made. Drift velocities from 0.1 up to 3000 cm/sec, in electric fields up to 25 000 V/cm, can be measured.
TL;DR: In this paper, the 50psec high-intensity (14 A, 20.5 MeV) beam from the EG&G/AEC electron linear accelerator was used with subnano-second timing techniques to make high-resolution (80 psec/m) neutron time-of-flight measurements over a short (25.35 m) flight path.
01 Oct 1970
TL;DR: In this paper, a velocity distribution function for a molecular beam formed from an aerodynamically accelerated source is developed from the Maxwell-Boltzmann distribution for an effusive source, which is presented in a form compatible with the time-of-flight measurement technique for the experimental determination of such distributions.
Abstract: : A velocity distribution function for a molecular beam formed from an aerodynamically accelerated source is developed from the Maxwell-Boltzmann distribution function for an effusive source. The distribution function is presented in a form compatible with the time-of-flight measurement technique for the experimental determination of such distributions. The expressions for several parameters of general interest, such as static temperature, speed ratio, energy, and velocity, are also presented. A description of a computerized data reduction technique for time-of-flight measurements is given. In addition, the effect of shutter functions and time delays in the accurate measurement of velocity distributions are discussed.
TL;DR: In this paper, the effect of a turbulent counter flow of liquid He II on the drift velocity of ions has been studied in a triode cell near 1 degree K. The results were consistent with the trapping of ions in superfluid turbulence.
Abstract: The effect of a turbulent counter flow of liquid He II on the drift velocity of ions has been studied in a triode cell near 1 degree K. It was found that when the ion drift velocity in the applied field and the normal fluid flow were in the same direction then the apparent ion velocity was enhanced with a velocity increase greater than the maximum normal fluid velocity through the holes of the grid, while the critical velocity for a discontinuity was only slightly affected by the normal fluid flow. Negative ions were more strongly affected than positive ions. The results were consistent with the trapping of ions in superfluid turbulence. The ions were trapped and then released closer to the collector so that their flight distance and hence their measured time of flight was effectively shortened to give an apparent increase in velocity. With trapping present it was not possible to determine whether the critical velocity of a discontinuity was to be considered as a velocity with respect to the superfluid or to the normal fluid. The origin and the spatial distribution of the turbulence are discussed and it is concluded that ion trapping occurred in superfluid vorticity which had been fed back with the normal fluid passing through the grid holes. A re-interpretation of the Gaeta diode experiment is proposed in terms of the recombination of ions trapped in the vorticity produced by the high-energy particles emitted from the source.
01 May 1970
TL;DR: Time of flight mass spectrometer for studies of ions produced by simulated micrometeoroid impact was used by as mentioned in this paper for the studies of ion production in simulated micro-drone impact.
Abstract: Time of flight mass spectrometer for studies of ions produced by simulated micrometeoroid impact