摘要:

The system described selects undistorted pulses and digitizes them for multichannel pulse‐height analysis. The system consists of a double RC differentiating linear amplifier, a low jitter gated single‐channel analyzer, a linear gate, and an analog‐to‐digital converter (ADC). The ADC is comprised of a simple discharge‐type pulse‐height to time converter, gating a temperature compensated 2‐Mc astable multivibrator. A temperature change of 25°C results in an over‐all gain change of 1%. Baseline shift is minimized by direct coupling. At an input rate of 100 000 pulses/sec the spectrum shifts by less than 1%. Pileup events are rejected by a unique baseline crossing discriminator. The rejection efficiency is about 80%. The apparent pulse width, for pileup considerations, is thereby reduced from 1.5 to 0.25 &mgr;sec. The circuits and their performance are discussed.

ISSN:0034-6748    

DOI:10.1063/1.1718360

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

Design parameter and performance of a simple automatic phase‐control system for a GR 1209‐B triode oscillator are described. The frequency modulation of the oscillator was achieved by varying the B+voltage of the oscillator tube, so that the resonance circuit does not have to be modified, and the described system will change neither the frequency range nor the calibration of the GR 1209‐B oscillator.

ISSN:0034-6748    

DOI:10.1063/1.1718361

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

An automatic torque balance has been constructed for use in studying the magnetic properties of thin ferro‐magnetic films. The automatic servo force balancing technique using a photoelectric pickoff has been applied to a fused‐silica torsion fiber suspension. A sample up to 600 mg in weight can be handled. The data are automatically recorded by an X‐Y plotter. Sensitivity of 10−6dyn‐cm and a response time of a fraction of a second have been obtained, providing a significant improvement over similar instruments previously used. An appropriate set of coils provides the magnetic fieldH. Since the torque on a sample is given byM×H=L, measurement of torque affords a means of studying the behavior of the magnetizationM. Provision is made for observing torque either parallel or perpendicular to the film surface. The sensitivity available will permit the study of 1‐cm‐diam films as thin as one‐half an atomic layer under ideal conditions. Examples are given of the measurement of the saturation magnetization, remanent magnetization, anisotropy constant, and coercive field on a 35‐Å film, showing the quality of the data. The anisotropy field and the squareness are calculated from the above quantities. Observations of rotational hysteresis loss are also discussed.

ISSN:0034-6748    

DOI:10.1063/1.1718362

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

An analysis of the use of angular modulation of the dc magnetic field used in electron paramagnetic resonance is presented. The equations which are derived show that angularly dependent paramagnetic resonance lines may be separated from angularly independent lines. Experiments with Cr2+in CdS show agreement with the theory.

ISSN:0034-6748    

DOI:10.1063/1.1718363

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

A practical infrared sensing apparatus has been developed to profile the temperature distribution of small complex structures without affecting the temperature distribution by the temperature sensing element. The sensitivity is 60°C for some materials, and the resolution is 1.3 mils.

ISSN:0034-6748    

DOI:10.1063/1.1718364

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

The resolution function of a 9‐in.‐diam by 10‐in.‐long cylindrical NaI(Tl) crystal for incident electrons of 55‐, 72‐, and 83‐MeV energy has been measured. A wedge magnet defined the electron energy. Spark chambers were used on either side of the magnet to insure against spurious scattering of electrons and to estimate the magnet system momentum spread. The most probable pulse height from the crystal varied linearly with electron energy. The pulse‐height distribution had a full width at half‐maximum of 13.4 +0.3 or −0.7%.

ISSN:0034-6748    

DOI:10.1063/1.1718365

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

Q‐spoiling is observed when an easily vaporized absorbing film located within the resonant structure of a ruby laser is destroyed by initial stimulated emission. Two features of this new technique are operational simplicity and no severe power handling limitations. The resulting laser output is characterized by a single giant pulse of micro‐second duration whose rise time (in the 20‐ to 40‐nsec range) is at least as fast as reported for Q‐spoiling by Kerr‐cell shutters.

ISSN:0034-6748    

DOI:10.1063/1.1718366

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

Superconducting magnets of sufficiently high inductance can be damaged by overheating during an accidental transition to the resistive state. Possible protection circuits are analyzed theoretically, and some of the practical consequences of the analysis are summarized.

ISSN:0034-6748    

DOI:10.1063/1.1718368

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

It has been found possible to evacuate hydrogen from a container into the air by the use of a heated Pd or PdAg alloy diaphragm. This effect is not the expected diffusion of hydrogen from a region of high hydrogen pressure to a region of lower hydrogen pressure, but a true pumping from a region of low hydrogen concentration to a region of higher hydrogen concentration. This pumping occurs only if the region of higher hydrogen concentration is in an oxidizing atmosphere and the region of lower hydrogen concentration is in a reducing atmosphere or a good vacuum. Pumping speeds for hydrogen up to 0.25 liter/sec per cm2of diaphragm have been observed for Pd and Pd‐25% Ag alloy 0.004 in. thick while operating between 500 and 600°C. It has been found possible to pump down to a hydrogen pressure of 10−9mm Hg while the hot Pd diaphragm was exposed to air. Ti and Ni diaphragms were found to exhibit similar pumping characteristics, but much lower pumping speeds were observed.

ISSN:0034-6748    

DOI:10.1063/1.1718369

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

Using an electron bombarded target the presence of silicone vapor was detected in the vessel of a bakeable ultra‐high vacuum system made of stainless steel exhausted by a silicone oil diffusion pump. Silicone molecules temporarily adsorbed on the target were desaturated by the impinging electrons and polymerized to form a deposit. The deposit thickness was measured by multiple‐beam interferometry. The diffusion pump was charged with silicone 704 and fitted with a chevron (trap II) and a container trap (trap I) next to the vessel. Liquid nitrogen cooling both the chevron and container‐type trap next to the vessel after baking (pultimate≃10−9Torr) gave a deposit growth rate of <5 Å/h. When the chevron trap was not operated during ultra‐high vacuum pumping the container‐type trap condensed sufficient oil vapor for the vessel to be contaminated when the vessel and trap were subsequently baked. The contamination rate measured during baking was dependent on the time the system had been previously under ultra‐high vacuum without the chevron trap being cooled. Ultra‐high vacuum pumping for 38 h at 10−9Torr gave rise to a deposit growth rate of 160 Å/h on the next baking cycle. The contamination rate was reduced to its lowest amount during baking (35 Å/h) when the chevron baffle was cooled throughout the pumping cycle. Using a new silicone fluid (705) gave a deposit growth rate of about one‐half to one‐quarter of fluid 704.

ISSN:0034-6748    

DOI:10.1063/1.1718370

出版商:AIP    

年代:1963

数据来源: AIP