摘要:

Spark chambers have been used in conjunction with photographic emulsion to investigate the accuracy and reliability in the location of primary cosmic rays in emulsion exposed at balloon elevations. The location of these primaries in the emulsion stack has been determined using measurements made on spark chamber photographs. A sample of 118 primaries withZ>1 which did not interact in the emulsion target has been used to calibrate the positions of the emulsions with respect to the spark chambers. The standard deviations of coordinate location errors in the emulsion plane and perpendicular to the emulsion plane were both 0.2 mm after calibration. The standard deviation of errors in the projected angles in the emulsions for these primaries was 0.2°. The mean and standard deviation of errors in the dip angles for these same events were 0.1 and 0.2°, respectively. A total of 191 out of 192Z>1 primaries, and 24 out of 39Z=1 target interacting primaries have been located in the emulsion without significant ambiguity. All the 63Z=1 noninteracting primaries with energies greater than 50 GeV have also been located in the emulsions without any ambiguities. Scanning efficiencies for theZ>1 primaries and theZ=1 noninteracting primaries were both about 100%. The scanning efficiency for theZ=1 target interacting primaries was approximately 43%. The scanning time required for the location ofZ>1 andZ=1 primaries which did not interact in the emulsion target was 2–3 h. Corresponding scanning times for the location ofZ>1 andZ=1 target interacting primaries were on the order of 6–8 h and two to four days, respectively.

ISSN:0034-6748    

DOI:10.1063/1.1684472

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

A new spectrometer for conducting laser electron paramagnetic resonance experiments on gases is described. This spectrometer yields at least an order of magnitude better sensitivity than the first spectrometer used in this type of investigation.

ISSN:0034-6748    

DOI:10.1063/1.1684473

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

A method for subnanosecond pulse measurements ofI‐Vcharacteristics is described. The sample is mounted at the end of a transmission line and the incident and reflected pulse is observed. In this way the sample resistance is compared with the known impedance of the coaxial transmission line and no current measuring series resistance is needed. Short pulse risetimes (170 psec) are obtained and difficulties which arise from the current measuring resistor, like temperature dependence and nonlinearity at high currents, do not obscure the measurements.

ISSN:0034-6748    

DOI:10.1063/1.1684474

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

For the study of bulk properties of electron excited semiconductors, it is necessary to apply high energy electrons for excitation which have a large penetration depth. A pulsed electron gun designed for investigating semiconductors under high excitation is described. It generates rectangular electron beam pulses with current densities up to 20 A/cm2. The profile of the current density in the focus plane is of Gaussian shape, its half‐width being up to 410 &mgr;. The electron energy can be varied from 160 to 300 keV, the pulse duration from 20 to 1000 nsec with a shortest risetime of 5 nsec without deviating from rectangular shape. The repetition frequency can be varied from 50 Hz down to single shots. The pulses are triggered from earth potential allowing easy investigation of time dependent effects. As a first application, time behavior of laser action of CdS single crystals is reported.

ISSN:0034-6748    

DOI:10.1063/1.1684475

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

A 70 Gc microwave interferometer for plasma density measurements has been constructed which separates the time varying amplitude and phase signal components induced by the plasma. A superheterodyne technique is used with amplitude limiting and phase detection at the 30 Mc intermediate frequency. Amplitude detection is performed prior to limiting. Phase stability is achieved by locking the local oscillator frequency to the sum or difference of the master oscillator and intermediate frequencies with an AFC loop.

ISSN:0034-6748    

DOI:10.1063/1.1684476

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

An experiment was designed in which shearing forces acting on a film of shear sensitive liquid crystals could be measured directly while additional instrumentation was used to measure the peak spectral intensity of the light scattered by the substance. A liquid crystals sample of low temperature sensitivity was tested and a calibration curve was obtained with a linear slope of 0.208 (g/cm2)/nm from 0 to 3 g/cm2.

ISSN:0034-6748    

DOI:10.1063/1.1684477

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

A control system has been designed for high speed photographic diagnostics based on the action of a rotating mirror. Built from simple circuitry and readily available standard delay units, it can operate independently of the mechanism driving the mirror. The system displays an over‐all jitter of less than 0.05%. It has been used successfully in the accurate superposition of repetitive pulsed discharge images on film.

ISSN:0034-6748    

DOI:10.1063/1.1684478

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

This note describes a composite window design which will allow visual or photographic observation and permit ir irradiation of test materials simultaneously in an ultrahigh vacuum system. The uhv compatibility has been ascertained by irradiating the sealant materials with a CO2laser while monitoring desorbed species with a quadrupole mass spectrometer.

ISSN:0034-6748    

DOI:10.1063/1.1684479

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

An NMR spectrometer is described which allows a direct plot of the Knight shift in metals to be recorded. The device uses a wide field range field‐to‐frequency lock unit with the output of the entire spectrometer being directly proportional to the Knight shift. Preliminary results of the field dependence of the Knight shift in aluminum obtained using the spectrometer are given.

ISSN:0034-6748    

DOI:10.1063/1.1684480

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

A technique is described for monitoring the thickness of transparent thin films growing on heated polished substrates (as in chemical vapor deposition). Thermal energy, radiated by a substrate and transmitted by a growing film, undergoes optical interference as a result of multiple reflections between the substrate‐film and film‐ambient interfaces. A narrow bandpass detector is used to measure the transmitted intensity and film thickness is correlated with the maxima and minima of the detector output. Using a 1P21 photomultiplier tube and a 6000 Å interference filter (90 Å half‐width) this technique has been applied for substrate temperatures as low as 800°C and thickness in the range of 1000–6000 Å with an accuracy of ± 100 Å. A special comparison technique is described which operates by sampling, storing, and subtracting signal intensities obtained from two substrates. Using this technique it is possible to terminate deposition of the outer film of a duplex combination (500 Å of Al2O3on SiO2, for example) within 25 Å of the chosen thickness.

ISSN:0034-6748    

DOI:10.1063/1.1684481

出版商:AIP    

年代:1970

数据来源: AIP