ISSN:0034-6748    

DOI:10.1063/1.1740871

出版商:AIP    

年代:1947

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1740872

出版商:AIP    

年代:1947

数据来源: AIP

摘要:

It is shown how punched‐card‐relay calculators can be used for solving ordinary linear differential equations of sixth and lower order. The differential equations are replaced by difference equations which can be solved by the relay calculators automatically step by step. The final solution is obtained by repeating the integration several times, each time computing the truncation error and applying it as a correction in the subsequent integration.

ISSN:0034-6748    

DOI:10.1063/1.1740873

出版商:AIP    

年代:1947

数据来源: AIP

摘要:

An instrument is described which will detect and record the alpha‐disintegration rate of prepared radioactive samples even though soft beta‐radiation up to 5×109disintegrations per minute may also be present. The counting losses arising from the detector, electronic amplifier, scaler, and recorder total 0.8 percent with an alpha‐counting rate of 105counts per minute. The instrument employs a proportional counter through which 99 percent CH4at one atmosphere slowly flows. The proportional counting region is approximately 300 volts in length, with 0.5 percent change in counting rate in an interval of 200 volts. Thin radioactive samples deposited on metal disks up to 2.5 cm in diameter are easily inserted into the counter volume by means of a special gas lock. The counter detects 0.50 of the disintegrations from a thin radioactive sample. The counter background can be maintained at about 14 counts per hour. A high vacuum, low geometry attachment provides reductions in geometry down to at least 10−5of the sample counting rate. Some theory of gas‐flow proportional counters is presented along with details of the instrument construction.

ISSN:0034-6748    

DOI:10.1063/1.1740874

出版商:AIP    

年代:1947

数据来源: AIP

摘要:

A method is described of producing metallic replicas from gratings by electro‐deposition of copper. It is possible to obtain concave replicas from a convex original grating—either metallic or glass. The optical figure and the grating qualities of the replicas are tested and shown in Figs. 2 to 6.

ISSN:0034-6748    

DOI:10.1063/1.1740875

出版商:AIP    

年代:1947

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1740876

出版商:AIP    

年代:1947

数据来源: AIP

摘要:

A method has been developed for determining absolute numbers of neutrons in terms of helium production in the B(n,&agr;)Li reaction. We are able to report preliminary measurements of the number of neutrons emitted per second from a certain Ra+Be source; i.e., source called No. 38, which contains 504 millicuries of Ra, was found to emit (5.5±0.4)×106neutrons per second.

ISSN:0034-6748    

DOI:10.1063/1.1740877

出版商:AIP    

年代:1947

数据来源: AIP

摘要:

A grounded grid oscillator and a single dee resonant system for use with a frequency modulated cyclotron are described. 7.5‐Mev deuterons have been accelerated with dee voltages up to 15 kv and a frequency range from 9.5 to 12 megacycles. 15‐Mev protons have been accelerated with voltages up to 11 kv and a frequency range from 19 to 24 megacycles. Coupling constants, phase correction, amplitude modulation, and discharge phenomena are discussed.

ISSN:0034-6748    

DOI:10.1063/1.1740878

出版商:AIP    

年代:1947

数据来源: AIP

摘要:

A coincidence circuit with a resolving time of from 10−9to 10−10second is described. It will operate satisfactorily with a 20‐db variation in the pulse energy and discriminate against non‐coincident pulses occurring at a rate of from 108to 109per second. Experimental results are given.

ISSN:0034-6748    

DOI:10.1063/1.1740879

出版商:AIP    

年代:1947

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1740880

出版商:AIP    

年代:1947

数据来源: AIP