Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Electronic Resource  (100)
  • 1990-1994  (34)
  • 1980-1984  (38)
  • 1975-1979  (28)
  • 1
    Electronic Resource
    Electronic Resource
    Collinear reactive scattering of state-selected H+2+He→HeH++H: A method for probing dynamical resonances (1991)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 94 (1991), S. 8615-8617 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We report on an experimental geometry for studying dynamical resonances in bimolecular collisions. The method is sensitive to atom–diatom reactions at low angular momentum and low impact parameter corresponding to the collinear coordinate. State-selected reaction probabilities for H+2+He→HeH++H were measured at c.m. scattering angles θ=0° and 180°; the collision energy was scanned from 0.35–1.90 eV.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.460718
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    State-selected reactive scattering. II. He+H+2→HeH++H (1991)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 95 (1991), S. 4894-4904 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The endoergic reaction He+H+2→HeH++H is investigated in a molecular-beam experiment as a function of H+2 vibrational energy at c.m. collision energies between 0.3 and 1.9 eV. Reactant ions generated by resonantly enhanced four-photon ionization are impulsively accelerated to collide with a beam of He. Time-of-flight velocity distributions of HeH+, measured at one laboratory angle, yield the differential cross section at c.m. angles θ=0° and 180°. A shift from "He rebound'' to "H+ stripping'' behavior accompanies the enhancement in the cross section as the H+2 vibrational energy increases, which matches previous studies at higher collision energy. Small-impact-parameter events produce HeH+ with less recoil velocity (more internal energy) than those at large impact parameters. Within the limits of sensitivity and resolution (ΔE≈0.15 eV), definitive resonance features in the collision energy dependence of dσ/dω are not evident. Improvements in the technique to enable such observations are suggested.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.461705
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    State-selected reactive scattering. I. H+2+H2→H+3+H (1991)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 95 (1991), S. 4877-4893 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Cross sections for the reaction H+2+H2→H+3+H, differential in scattering angle and recoil energy, are measured in a molecular-beam experiment at c.m. collision energies of 1.5, 2.3, 3.5, and 5.3 eV. Resonantly enhanced four-photon ionization prepares H+2 in selected vibrational-state distributions, allowing a systematic exploration of the effects of reactant energy on the product angular and energy distributions. Angular data are interpreted on the basis of competition between H+3 formation and collision-induced dissociation. The nominal atom-transfer (AT) and proton-transfer (PT) processes are identified respectively with forward and backward scattered H+3. Effects of reactant energy on AT and PT cross sections in H+2+H2 are compared with previous observations on D+2+H2 and H+2+D2. The fraction of the available energy appearing as H+3+H recoil ranges from 26% to 39% depending on reactant conditions. Previous surface-hopping trajectory calculations successfully predict most of the observed trends. Evidence is given for the existence of long-lived H+3 with internal energy in excess of the dissociation limit.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.461704
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Anomalous losses of deuterium–deuterium fusion products in the Tokamak Fusion Test Reactorf| (1994)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 1 (1994), S. 1469-1478 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In the Tokamak Fusion Test Reactor (TFTR) [International Conference on Plasma Physics and Controlled Nuclear Fusion Research, Wurzburg, Paper No. A-2-2 (International Atomic Energy Agency, Vienna, 1993)] there have been at least three types of anomalous loss of alpha-like deuterium–deuterium (D–D) fusion products: (1) a magnetohydrodynamic (MHD)-induced loss of D–D fusion products correlated with Mirnov and fishbone-type oscillations and sawtooth crashes, (2) a slow "delayed'' loss of partially thermalized D–D fusion products occurring without large MHD activity, and (3) ion cyclotron resonance heating (ICRH)-induced loss of D–D fusion products ions observed during direct electron heating experiments, and possibly also during 3He minority heating. In this paper each of these will be reviewed, concentrating on those due to MHD activity, which are the largest of these anomalous losses. The experimental results are compared with numerical models of various fusion product transport mechanisms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.870697
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Validation of spatial profile measurements of neutron emission in TFTR plasmas (invited) : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 4517-4522 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The TFTR multichannel neutron collimator provides spatially localized information on nuclear reaction rates in fusion plasmas. Absolutely calibrated NE 451 ZnS scintillators detect chord-integrated neutron emission along ten vertical sightlines, which are defined by a massive shielding structure in the facility basement. If such observations are to be of value, virgin neutrons along each sightline must be distinguishable from a background of gamma rays and scattered neutrons, and the measurements must be sufficiently precise, over a wide range of plasma conditions, to allow meaningful comparison with results of transport analysis computer codes. As a useful check, the volume-integrated neutron emission must agree with independent measurements of the global neutron source strength. Although NE 451 detectors are insensitive to gamma rays and to neutrons with energy less than ∼2 MeV, the scintillation pulse height distribution depends on both the incident neutron energy spectrum and the physical parameters of the individual detector. In order to establish the validity of our measurements, we have carried out a detailed characterization of our detectors, including computer modeling of scintillation pulse height spectra and of temporal pulse pileup effects in the counting circuitry. Satisfactory operation of the system has been demonstrated for all deuterium plasmas encountered in TFTR. The detector modeling, together with further laboratory measurements, will enable us to prepare for deuterium–tritium experiments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143708
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Control of the neutron detector count rate by optical imaging : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 4539-4541 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The signal processing electronics used for the NE451 detectors on the TFTR multichannel neutron collimator are presently showing saturation effects at high counting rates equivalent to neutron yields of ∼1016 n/s. While nonlinearity due to pulse pileup can be corrected for in most present TFTR experiments, additional steps are required for neutron source strengths above ∼3×1016 n/s. These pulse pileup effects could be reduced by inserting sleeves in the collimator shielding to reduce the neutron flux in the vicinity of the detectors or by reducing the volume of detector exposed to the flux. We describe a novel method of avoiding saturation by optically controlling the number neutron events processed by the detector electronics. Because of the optical opacity of the ZnS-plastic detectors such as NE451, photons from a proton-recoil scintillation arise from a spatially localized area of the detector. By imaging a selected portion of the detector onto a photomultiplier, we reduce the effective volume of the detector in a controllable, reversible way. A prototype system, consisting of a focusing lens, a field lens, and a variable aperture, has been constructed. Results of laboratory feasibility tests are presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143713
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Remotely controlled illumination system for TFTR in-vessel inspection : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 4738-4740 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Internal components of the Tokamak Fusion Test Reactor (TFTR) vacuum vessel are inspected routinely during nonoperational periods using in vacuo illumination probes in conjunction with a periscope/camera viewing system. The probes presently in use must be inserted manually by personnel in the test cell, and thus are not suitable during the DT operating phase of TFTR. A new probe concept was developed which is compact, mechanically robust, and remotely operated. Each probe consists of four 650 W tungsten–halogen lamps mounted on an inconel reflector and a rotatable, cylindrical shutter which protects the lamps from deposits during plasma operation. Six probes will be permanently mounted inside the vacuum vessel at top and bottom ports which are distributed to provide the most uniform illumination practicable. The probe design and results from prototype testing will be presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143625
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Erratum: "Anomalous losses of deuterium–deuterium fusion products in the Tokamak Fusion Test Reactor'' [Phys. Plasmas 1, 1469 (1994)] (1994)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 1 (1994), S. 3138-3138 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.870506
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Feedback for High EEG Alpha Does Not Maintain Performance or Mood During Sleep Loss (1976)
    Oxford, UK : Blackwell Publishing Ltd
    Psychophysiology 13 (1976), S. 0 
    Details
    ISSN: 1469-8986
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine , Psychology
    Notes: Can performance and mood during sleep loss be maintained by self-induced high EEG alpha activity? In a previous study, most of the performance and mood measures showed sleep-loss impairment regardless of EEG alpha level, but attention and reported sleepiness were less impaired for the high-alpha group (although the differences were of doubtful significance). A constructive replication was carried out. In Group A (N=10) auditory feedback was contingent on high alpha, and in Group B (N=10) auditory feedback was contingent on low alpha and low theta. All subjects were repeatedly measured on auditory vigilance, addition, immediate recall, and feelings of sleepiness for 40 hrs during which no sleep was permitted. Sixty min of EEG feedback were given during each block of 220 min. Group A did produce significantly more alpha for the first 24 hrs but this difference was not maintained. Both groups had significant sleep-loss impairment on all measures. There were no significant differences between the groups in the amount of impairment. Self-enhanced EEG alpha activity does not prevent impairment of performance or mood during sleep loss.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1469-8986.1976.tb03338.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Sleep During and After Gradual Sleep Reduction (1977)
    Oxford, UK : Blackwell Publishing Ltd
    Psychophysiology 14 (1977), S. 0 
    Details
    ISSN: 1469-8986
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine , Psychology
    Notes: To determine: 1) the minimum amounts of sleep subjects would tolerate, 2) the changes in EEG sleep measures, and 3) whether subjects would revert to baseline sleep after study termination, 4 couples gradually reduced their sleep. Three couples reduced their TST in 30-min steps from a baseline of 8 hrs and one couple from a baseline of 6.5 hrs. Subjective estimates of sleep time, sleep quality, and mood were collected daily. Home EEG sleep recordings were obtained 3 nights a week.Two of the 8-hr sleepers reduced their sleep to 5.5 hrs, 2 to 5.0 hrs, and 2 reached 4.5 hrs. These 6 subjects continued sleeping 1 to 2.5 hrs below baseline amounts a year after reduction terminated. The 6.5-hr baseline couple reached 5.0 hrs and returned to 6.5 hrs TST during follow-up.Stages W, 2, and REM decreased significantly in absolute amounts. Percentage of stages W and 2 also decreased significantly. REM percent remained constant. Stage 3 was constant while stage 4 increased in both absolute and relative amounts. REM cycle length remained constant. Stage 4 rebound on 7-hr nights was not observed during times of greatest sleep reduction. Occurrences of stage REM within 10 min of stage 1 onset were observed in 2 subjects when their TST was below 6.5 hrs.Our results are consistent with other studies of shortened sleep, indicating that TST is the major determinant of sleep-stage characteristics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1469-8986.1977.tb01168.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...