摘要:

The irradiation effects and the increase of neutron yield from the deuterium‐deuterium reaction in tantalum has been studied at a bombarding energy of 350 kev and a target current 100 &mgr;a. Saturation (the neutron yield becomes a steady maximum) is reached in a new target, maintained at temperatures below 45°C, after about 2 hours of steady bombardment or on the order of 1 coulomb of deuterons per square centimeter. The irradiated targets were annealed at temperatures from 45°C to 770°C. A thermal analysis shows that a prominent exothermic maximum in the annealing spectrum occurs at approximately 612°C. This maximum is associated with an increase in pressure, indicating an abrupt increase in diffusion of deuterium from the target at this temperature. From a study of diffusion of deuterium from the specimen at three temperatures, an activation energy of 0.24 ev is calculated for diffusion of deuterium in tantalum.X‐ray traces were taken of the specimen before and after bombardment and after annealing. These showed an expansion of the lattice together with changes in line intensities indicating a distortion in the lattice structure.

ISSN:0021-8979    

DOI:10.1063/1.1735448

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

A chopped‐light spot has been used to explore the photoresponse of siliconp‐njunction surfaces. Anomalous channel responses extending in some cases to distances of 100 mils or more, have been observed on accumulation layer and intrinsic barrier surfaces. The phase shift of the induced ac photocurrent is measured as a function of the distance of the light spot from the junction, and phase shifts of more than 380° have been observed for the anomalous channels. Experimental evidence is offered to show that the excessive phase shift is due to multiple trapping of the injected carriers at surface interface states. Additional evidence indicates that the anomalous channels are a result of an interaction of the fringing field with the slow surface states.

ISSN:0021-8979    

DOI:10.1063/1.1735449

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

A series of x ray and etch pit experiments has been performed to determine some of the effects of temperature on the perfection of surface layers in LiF. It was found that the perfection of a cleaved surface is substantially increased at temperatures near the melting point, that rearrangement and annihilation of dislocations takes place at much lower temperatures, and that rapid cooling promotes the formation of shallow dislocation loops.

ISSN:0021-8979    

DOI:10.1063/1.1735450

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

The bulk magnetic susceptibilities of single gallium crystals and polycrystalline gallium spheres were measured at 25°C. The following anisotropic diamagnetic susceptibilities were found:aaxis (−0.119±0.001)×10−6emu/g,baxis (−0.416±0.002)×10−6emu/g, andcaxis (−0.229±0.001) emu/g. The susceptibility of the polycrystalline spheres, assumed to be the average value for the bulk susceptibility of gallium, was (−0.257±0.003)×10−6emu/g at 25°C, and (−0.299±0.003)×10−6emu/g at −196°C. The susceptibility of liquid gallium was (0.0031±0.001)×10−6emu/g at 30°C and 100°C. Rotational diagrams of the susceptibilities in the three orthogonal planes of the unit cell were not sinusoidal. The anisotropy in the single crystals was presumably caused by the partial overlap of Brillouin zone boundaries by the Fermi‐energy surface. The large change in susceptibility associated with the change in state was attributed to the absence of effective mass influence in the liquid state.

ISSN:0021-8979    

DOI:10.1063/1.1735451

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

The dielectric constant and loss tangent of single crystals of BaTiO3were measured as a function of temperature in the frequency range of 8.2 to 12.4 kMc. The technique consisted of looking for transmission resonances through the crystal whenever its thickness became &lgr;/2 (where &lgr; is the wavelength in the material). From the Curie‐Weiss behavior of the dielectric constant in the paraelectric region, theAconstant was determined to be 3.77×10−5°C−1.

ISSN:0021-8979    

DOI:10.1063/1.1735452

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

The magnitude, duration and spatial distribution within a solid body (Plexiglas) of the transient stress disturbance generated by an electric detonator detonated in intimate contact with the body has been experimentally determined. The technique is to affix to one surface of the body a small pellet of the same material, which flies off when the disturbance reaches the surface, the velocity of the pellet being determined. The complete stress‐time curves are built up by using pellets of several thicknesses. Three types of detonators have been used with these being placed flat ended against the surface of a Plexiglas block. A few were confined. The stress in the Plexiglas was found to be distributed more or less uniformly about the axis of the detonator. Along the axis both peak pressure and total momentum decreased with distance from the detonator: peak pressure exerted by an Olin Mathieson No. 6 Plasti‐cap ranged from 9500 lb/in.2at 1.25 in. from the detonator to 7000 lb/in.2at 2.0 in.; and the momentum ranged from 16×10−3lb‐sec/in.2at 1.25 in. to 9.0×10−3lb‐sec/in.2at 2.0 in. The disturbance lasted about two &mgr;sec. Similar results were obtained with the other detonators.

ISSN:0021-8979    

DOI:10.1063/1.1735453

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

The dc properties of a periodic focusing system consisting of a parallel pair of ladder lines, together with focusing plates parallel to the lines, are calculated. First, Laplace's equation is solved in an approximate way; following this, the paraxial‐ray equation for an electron sheet beam, injected into the system halfway between the ladder lines, is solved for perveance, plasma frequency, beam stiffness, and average beam potential. Finally, a numerical example is presented and discussed.

ISSN:0021-8979    

DOI:10.1063/1.1735454

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

Metal precipitates in junctions were found to cause excess reverse current below avalanche breakdown, which is conjectured to be due to Zener tunneling at localized high‐field points. This current varies asVnwherenis between 4 and 7. By a potential plotting method, it was shown that this excess current is not caused by a surface effect. Metal precipitates can be removed or prevented by ``gettering'' from surface layers. Metallic coatings and certain glassy oxide layers were investigated. Results indicate that layers of Ni and Zn have a limited gettering effect. Glassy layers, especially those of boron and phosphorus, have the greatest gettering effect.

ISSN:0021-8979    

DOI:10.1063/1.1735455

出版商:AIP    

年代:1960

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1735456

出版商:AIP    

年代:1960

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1735458

出版商:AIP    

年代:1960

数据来源: AIP