摘要:

A magnetically suspended rotor pressure gauge is described for measuring pressures below 10−4torr. The data are in good agreement with those obtained with a calibrated Alpert ionization gauge over the range 10−4to 5×10−8torr. When the gas in the vacuum system was frozen out with liquid helium, the rotor gauge recorded a residual pressure of about 5×10−10torr. A brief discussion is given of a number of effects which unless eliminated may introduce errors into the measurements at the lowest pressures.

ISSN:0034-6748    

DOI:10.1063/1.1746520

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

A very sensitive hydrostatic pressure transducer was made using a silicon tunnel diode. The transducer consists, essentially, of a tunnel diode shunted by a resistor which satisfies the stability conditions for operation in the amplifier mode. The advantages of the tunnel diode transducers are (1) small size, (2) sensitivity, and (3) versatility. Since the p‐n junction region is normally 1 mil in diameter or less, miniaturization is possible. Pressure sensitivities as high as 2 mv/v/psi were observed over a 60‐psi pressure range. Expressed in terms of gauge factor, the above sensitivity is equal to about 30 000. Such high sensitivities, within narrow pressure ranges, were achieved at pressures up to 20 000 psi. The pressure range as well as the pressure sensitivity in a chosen pressure interval can be varied very simply by adjusting the values of the shunt resistor and the current through the diode‐resistor combination. Even higher gauge factors can be obtained with other semiconductor materials.

ISSN:0034-6748    

DOI:10.1063/1.1746522

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

A computing program was developed for simultaneously tracing trajectories and classical, relativistic spin precessions around the zero gradient synchrotron (ZGS). Depolarizing resonances, previously predicted, were found and their properties were computed; there were 36 significant resonances, 12 of which were serious. A method is proposed for avoiding these 12 resonances by using two or four pulsed quadrupole magnets around the ZGS ring. These would rapidly shift &ngr;z, the vertical betatron oscillation frequency, at appropriate energies during the acceleration cycle. With this method, a proton beam, injected into the ZGS withP=1, would haveP>0.7 at the end of the acceleration cycle.

ISSN:0034-6748    

DOI:10.1063/1.1746524

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

The interaction of a beam of charged particles in an accelerator with the radio‐frequency cavity that provides the accelerating electric field has been investigated previously for the condition that the characteristic frequency of the cavity exactly coincides with a harmonic of the beam circulation frequency. In the present work an equivalent circuit is used to extend the self‐consistent analysis to situations where this condition is not satisfied. It is shown that by proper tuning (appropriate choice of cavity inductance) it is possible to minimize the power consumed in the external driving circuit by bringing the cavity‐wall currents into phase with the external generator. The power delivered to the beam and the cavity walls is not affected by the tuning. A high‐Q cavity is advantageous if the system is properly tuned. A numerical example is given which indicates that the necessary change in the eigen‐frequency is of the order of 1%, and that the resulting reduction in power requirements may be quite significant.

ISSN:0034-6748    

DOI:10.1063/1.1746527

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

An automatic ellipsometer for measurement of the thickness of thin films in the monomolecular range is described. The instrument is capable of pushbutton operation by untrained personnel, and has been in use in an industrial laboratory for about two years.

ISSN:0034-6748    

DOI:10.1063/1.1746529

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

An all‐electronic precision current integrator for use with a charged particle accelerator has been developed which eliminates the substantial deadtime normally associated with multicycle current integrators utilizing relays as their basic switching elements. Integration is accomplished in the conventional fashion of charging a precision condenser with the current to be integrated, electronically noting the completion of a predetermined voltage excursion and then returning the condenser to its initial charge state for repetition of the cycle. A unique feature of this integrator is the return of the integrating condenser to its initial charge state through the transfer of a precise amount of negative charge to the condenser by an all‐electronic charge transfer circuit. Integration continues during the charge transfer with no interruption and with no effect on the precision of integration. An electronic counter circuit interrupts the integration at the end of a preset number of cycles and gates off any associated equipment. Current range is approximately 1–500 &mgr;a. Accuracy at low currents is limited primarily by a total circuit leakage current of the order of 1.5×10−9amp. At higher currents, electrometer and other circuit instabilities limit accuracy to slightly better than 0.01%.

ISSN:0034-6748    

DOI:10.1063/1.1746532

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

A digital computer program called KICK (K‐meson Interaction Coplanarization and Kinematics), which carries out the analysis of complete bubble chamber events, is described. The program inputs data from a single‐track analysis program which has used raw track measurements to perform the spatial reconstruction of tracks and has fitted appropriate curves to them. KICK consists of a set of general processing or analysis routines, each of which is capable of carrying out one of the unique processing steps to which a given event may have to be subjected for proper analysis, for example, ``Input Event,'' ``Fit Vertex,'' ``Transform Variables Along Track,'' ``Output Results,'' etc. Also included is a set of event‐type control subroutines each of which, calling upon the proper sequence of these general processing routines, is able to carry out the desired analysis of a particular type of event. This program is in use on IBM 704/9's at many laboratories.

ISSN:0034-6748    

DOI:10.1063/1.1746534

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

An extensometer is described which, with an X‐Y recorder, draws stress‐strain curves for specimen extensions up to 33 in. It is designed so that the specimen contributes negligible energy to the follow‐up mechanism. Finger‐like sensors lightly contact the specimen at the bench marks. They are carried on ball bearing bushed carriages which are independently advanced by endless cables driven by reversible servo motors to keep the sensors on their starting positions on the specimen. Each motor also drives ten‐turn potentiometers which are connected in parallel to a power source available in the tensile tester. The differential voltage thus developed between the potentiometer contacts is proportional to the sensor spacing. It is balanced by an opposing voltage from a follow‐up potentiometer associated with the recorder chart drive so that the slightest movement of the sensors results in a proportional chart movement. The tensile tester load cell deflects the pen to trace a stress‐strain curve. Reference point spacings are automatically set at ½, 1, or 2 in. (or other) as selected. Installation is easily made, and the entire extensometer can be removed or replaced without tools.

ISSN:0034-6748    

DOI:10.1063/1.1746536

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

New automatic recording methods are described. One is the recording of the angular shift of a specific diffraction peak in a continuous line. The other is the recording of the angular shift of more than two diffraction peaks. The method of automatic recording of the thermal expansion coefficient is also described.

ISSN:0034-6748    

DOI:10.1063/1.1746538

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

The Hall effect has been widely utilized to measure magnetic fields. The relatively simple geometry of a Hall element suggested the use of such a device on a microscale as a probe to examine magnetic fields of small structures. Hall probes are described which were constructed with a sensitive area about 10×10 &mgr;. Fields of less than 0.01 gauss were found to be measurable using evaporated bismuth films. Probe fabrication techniques are described, and the factors affecting probe performance are discussed. A number of instrumentation systems, which have proven suitable for measuring small dc magnetic fields and high frequency ac fields, are presented. High accuracy (1%) of field measurement is readily attained.

ISSN:0034-6748    

DOI:10.1063/1.1746541

出版商:AIP    

年代:1962

数据来源: AIP