摘要:

Reliable forming techniques for the preparation of doubly curved LiF x‐ray monochromators are described. These techniques are applicable to the formation of doubly focusing one piece monochromating crystals with geometries suited to a wide range of experimental requirements. The resulting dislocation structures were analyzed and utilized in the development of the techniques and are presented as a guide for the preparation of similar focusing crystals.

ISSN:0034-6748    

DOI:10.1063/1.1717570

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

Apparatus for obtaining 14‐Mev neutrons in pulses of approximately 10‐&mgr;sec duration is described. It employs a gaseous discharge in deuterium at low pressure whereby deuterons of up to 180‐kev energy are generated and accelerated into a tritiated zirconium target. This method provides a much greater abundance of deuterons than has been obtainable with ion guns. In its present form the device constructed has given yields approaching the theoretically expected value of 1010neutrons per pulse.

ISSN:0034-6748    

DOI:10.1063/1.1717571

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

A total absorption lead glass Cˇerenkov counter to be used as &ggr;‐ray and electron spectrometer in the 1–10 Gev region is described. The calibration of the counter with monoenergetic electrons shows its response to be linear at least up to 14 Gev. The pulse‐height spread improves with increasing energy and it is better than 10% (full width at half‐height) for energies above 5 Gev.

ISSN:0034-6748    

DOI:10.1063/1.1717572

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

Experiments on the mechanism and characteristics of a CO2‐CS2Geiger counter are reported, and circuits and methods of operation which satisfy the special requirements are described. Counter: The active part is 2⅞ in. in diameter and 16 in. long, filled to 1 atm, 95% CO2and 5% CS2. The cathode is copper and the anode is 0.005‐in.‐diam Chromel A. Characteristics: The electrons released by an ionizing particle become attached, probably to CS2. The self‐quenching action of the counter is excellent, no spurious counts are observed in the absence of electronic quenching. However, a dead time of several milliseconds must be imposed electronically because of the long interval during which the negative ions arrive at the anode. Method: An electronic quench is used which is triggered both by the CO2‐CS2counter and the anticoincidence ring. This serves to impose the required dead time and also to prevent the firing of the CO2‐CS2counter by mesons. Measurements: The plateau was measured to 1900 v above threshold and was found to be level to within 1% from 400 to 1600 v above threshold. The maximum drift time of the negative ions was found to be about 9 msec with a sharp cutoff. Tests with various combinations of gas indicated, but did not prove, that the charge carrier was CS2. The effects of common contaminants were determined. At voltages over 400 above threshold, 1% O2gave no detectable effect; 0.3% SO2gave a 2 to 3% reduction in counting rate. Extensive tests of the efficiency were made. Comparisons of the CO2‐CS2filling with an argon‐ethane filling gave identical results within the experimental error. No basis was found for supposing that there was any failure of the CO2‐CS2counter to register counts. Reliability: The counter described has been used for C14dating purposes over a long period of time. There has been no indication that there are variations in counting rate outside those expected on the basis of statistics. The counting rate for ``dead'' CO2in an iron shield 9 in. thick and after anticoincidence is 8 per min.

ISSN:0034-6748    

DOI:10.1063/1.1717573

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

A method of generating high power radio‐frequency pulses is described which utilizes the ``current dwell'' period which can occur when a thin wire is exploded by means of a high current. The rf oscillation occurs in a resonant circuit placed in series with the exploding wire. A circuit is described in which is obtained a 6‐&mgr;sec duration pulse of 2.74‐Mc oscillations.

ISSN:0034-6748    

DOI:10.1063/1.1717574

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

A simple technique for shunting pulsed, high field magnetic coils after the field has reached the maximum value is described.

ISSN:0034-6748    

DOI:10.1063/1.1717575

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

A burner capable of burning hydrogen and fluorine as premixed reactants at low pressures is described. The construction of the burner was such that the reaction, which is normally considered spontaneous when the gases come in contact, remained suppressed until the lip of the burner was reached. Combustion occurred over an extremely wide range of fuel‐oxidant ratios including mixtures rich in fluorine. The flame produced by the burner was flat and symmetrical in shape.

ISSN:0034-6748    

DOI:10.1063/1.1717576

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

A guided string acid saw for the strain‐free planar cutting of oriented single crystals is described. A Saran monofilament used as the acid carrying element is guided completely through the cut by a grooved blade serving the three‐fold purpose of guide, pressure device, and follower for a position sensing mechanism which automatically controls the feed. Guiding of the string results in a width of cut to string diameter ratio considerably lower than that of unguided acid saws. Bismuth and copper crystals have been cut with excellent results using this device.

ISSN:0034-6748    

DOI:10.1063/1.1717577

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

A new circuit is described for the generation of current step functions of long duration, having a short rise time and yielding a large steady current. The following set of values has been achieved: rise time, 1 &mgr;sec; duration, 320 &mgr;sec; current, 5000 amp.

ISSN:0034-6748    

DOI:10.1063/1.1717578

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

It is shown that a columnar geometry of electrical gaseous plasma may be examined by the conventional microwave cavity method, and results may be interpreted such that plasma electron densities considerably above that corresponding to ``resonance'' with the applied microwave frequency may be determined.

ISSN:0034-6748    

DOI:10.1063/1.1717579

出版商:AIP    

年代:1961

数据来源: AIP