摘要:

Recently revealed values for the energy monochromaticity and exit aperture in the Schwarz‐Hora experiment are found to be inconsistent with the claimed beam current by orders of magnitude using the Langmuir brightness relation. Accordingly, attempts to duplicate the reported experimental conditions appear futile, and claims for the effect based upon the quoted experimental conditions may be regarded with skepticism.

ISSN:0003-6951    

DOI:10.1063/1.1654083

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

Electron beams of relatively high currents (0.5 &mgr;A) and 50‐keV energy with observable modulability at optical frequencies can be produced without violating the Langmuir brightness relationship by shaping the beam in a ``filamentary'' structure, whereby each single‐beam ``filament'' fulfills the recently reported monochromaticity requirement (energy spread better than 10 meV). The monochromator and the electron‐optical‐beam ``shaper'' have to be made adjustable for accurate spatial coherence between the electron‐beam ``filaments''.

ISSN:0003-6951    

DOI:10.1063/1.1654084

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

Based on the direct tunneling model, the complete solution is obtained for the charge‐transport equation for MIS memory transistors. It is shown that the time dependence is linear in the microsecond range, roughly logarithmic in the millisecond range, and eventually saturates to a value determined by the physical characteristics of the device. For an oxide layer 20 Å thick, the theory predicts a switching time of about 45 &mgr;sec and saturation in about 150 sec.

ISSN:0003-6951    

DOI:10.1063/1.1654085

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

A cholesteric liquid‐crystal area detector has been used to make acoustical holograms at 5 MHz in water. The holograms were photographed by integrated time exposure and the original images reconstructed using laser light.

ISSN:0003-6951    

DOI:10.1063/1.1654086

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

The condition that the threshold current has to be less than the critical current in a superconducting injection maser is shown to be insufficient. Irrespective of the material, the number of states above the gap edge is too small to accommodate the overpopulation required to exceed all the losses in a superconductor.

ISSN:0003-6951    

DOI:10.1063/1.1654087

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

Resistivity measurements have been made on Nb cavities, as well as on Pb and Cu, at 296, 77, and 4.2 °K by means of a contactless induced‐current method. For superconductors, a constant magnetic field drives the material normal below the transition temperature. These measurements provide a simple means for initial material evaluation as well as a direct means of monitoring the effects of material parameters (purity, heat treatment, gas incorporation, etc.) on the electron mean free path. Approximate determinations ofHc,Hc1, andHc2can also be derived from these measurements. Normal‐state thermal conductivity and the Ginzburg‐Landau parameter &kgr; are calculated from the resistivity measurements.

ISSN:0003-6951    

DOI:10.1063/1.1654088

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

An oriented piezoelectric film has been incorporated in the insulator region of a silicon insulated‐gate field‐effect transistor to provide a sensitive high‐frequency strain transducer. With this device, strains as low as 10−8have been detected and gauge factors of roughly 7000 have been attained for applied ac strains at 5.6 MHz.

ISSN:0003-6951    

DOI:10.1063/1.1654089

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

A flood‐gun arrangement is shown to be useful in alleviating the sample‐charging problem in x‐ray photoelectron spectroscopy. Modest currents (<10−8A) of low‐energy electrons result in the shifting of photoelectron energy peaks to the proper positions and the reduction of the peak widths.

ISSN:0003-6951    

DOI:10.1063/1.1654090

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

One‐ and two‐photon absorption (at 5300 Å) thresholds for laser action in aqueous bromocresol green and aqueous bromocresol purple were measured, and a novel method of measuring gain, requiring only one photomultiplier, is reported.

ISSN:0003-6951    

DOI:10.1063/1.1654091

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

High‐field measurements of decreased response time, gain saturation, and enhanced signal‐to‐noise ratio are reported as evidence of minority‐carrier sweepout in 0.09‐eV HgCdTe photoconductors.

ISSN:0003-6951    

DOI:10.1063/1.1654092

出版商:AIP    

年代:1972

数据来源: AIP