摘要:

A variable microwave noise temperature standard having an output from below 40 to above 370 K is described. This temperature standard is unique in that a closed cycle low temperature cooler used in conjunction with a proportional control heater network provides continuously variable low temperatures which are independent of the boiling temperatures of cryogenic liquids and may be readily changed and known with an accuracy of better than 1.0 K. A variable temperature output is obtained without the use of a microwave attenuator thus eliminating the inherent errors associated with the attenuator. The output noise temperature is completely calculable using measured parameters (i.e., thermal temperatures, waveguide insertion loss, and impedance mismatch factors) and as a result may qualify as a primary noise standard.

ISSN:0034-6748    

DOI:10.1063/1.1684365

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

An experimental system for Mo¨ssbauer studies following Coulomb excitation or nuclear reactions is described. A drift‐free high velocity Doppler spectrometer is incorporated in the apparatus, and a closed cycle helium refrigerator is used for cooling the target and absorber to low temperatures. The system also operates successfully as a conventional Mo¨ssbauer spectrometer with radioactive sources.

ISSN:0034-6748    

DOI:10.1063/1.1684366

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

This paper describes the theory and construction of apparatus for the vapor deposition of highly resistive, highly oriented, piezoelectrically active cadmium sulfide films from the constituent elements. The cadmium and sulfur are evaporated from a double coaxial isothermal source, the composition of the vapor beam being determined predominantly by the area of an orifice in each source. The source operates at 420°C, and condensation rates of 300 Å/sec are readily obtained. The deposition rate may be varied over a wide range (say, 15 to 1) with little resultant change in resistivity. Films were deposited on fused quartz to serve as electromechanical transducers. A shear mode coupling constantktof 0.12 was measured. The longitudinal mode signal level was 46 dB below that of the shear mode at the upper 3 dB shear mode frequency. A longitudinal modektof 0.12 has been obtained with a shear mode suppression of 60 dB.

ISSN:0034-6748    

DOI:10.1063/1.1684367

出版商:AIP    

年代:1970

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1684368

出版商:AIP    

年代:1970

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1684369

出版商:AIP    

年代:1970

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1684370

出版商:AIP    

年代:1970

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1684371

出版商:AIP    

年代:1970

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1684373

出版商:AIP    

年代:1970

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1684375

出版商:AIP    

年代:1970

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1684376

出版商:AIP    

年代:1970

数据来源: AIP