ISSN:0034-6748    

DOI:10.1063/1.1770937

出版商:AIP    

年代:1954

数据来源: AIP

摘要:

A 0.6 &mgr;abeam of He++ions has been produced and accelerated to 7.6 Mev in an electrostatic generator. The He++ion source, contained in the high voltage electrode of the generator, consists of a second small 400 kv electrostatic generator driven by the upper belt pulley of the main machine. He+ions obtained from a low voltage arc type ion source in the dome of the small generator pass through a region of low pressure gas to become doubly ionized before entering the main accelerating tube of the large generator.

ISSN:0034-6748    

DOI:10.1063/1.1770938

出版商:AIP    

年代:1954

数据来源: AIP

摘要:

A cylindrical liquid scintillation counter, 75 cm in diameter and 75 cm high has been used for the detection of neutrons, gamma rays, and cosmic ray &mgr; mesons. A delayed coincidence technique has been used to detect neutrons; the first pulse corresponding to a recoil proton or other associated event, the second pulse due to neutron capture in cadmium. The capture rate of neutrons in a solution containing toluene and cadmium has been calculated as a function of the cadmium to hydrogen ration by the Monte Carlo method and an experimental check performed. Detector design considerations and some possible uses are described.

ISSN:0034-6748    

DOI:10.1063/1.1770939

出版商:AIP    

年代:1954

数据来源: AIP

摘要:

The fraction of the charged particles traversing an absorber in a counter experiment which miss the last counter because of multiple Coulomb scattering in the absorber has been calculated for a general counter geometry. The results are presented in the form of graphs which give the fraction of surviving particles as a function of the counter geometry and the amount of multiple scattering in the absorber. It is shown that the effect of single scattering at large angles is very small.

ISSN:0034-6748    

DOI:10.1063/1.1770940

出版商:AIP    

年代:1954

数据来源: AIP

摘要:

A highly sensitive Giebe‐Scheibe apparatus for piezoelectric detection is described, incorporating the frequency sweeping technique of Perdok and van Suchtelen. Provision is made for observations over wide temperature ranges.

ISSN:0034-6748    

DOI:10.1063/1.1770941

出版商:AIP    

年代:1954

数据来源: AIP

摘要:

A negative muon beam effectively free of pions and secondary particles has been obtained at the 102 Mev &pgr;−channel of the Chicago synchrocyclotron by placing a graphite filter 36.0 g/cm2thick in the beam. The emerging muons were magnetically deflected from the main beam and their energy was shown to be about 50 Mev. A radiochemical method for determining the &pgr;−/&mgr;−ratio in the range 10 to 0.01 was used to demonstrate the purity of the negative muon beam.Although not directly tested, his method for producing a muon beam should work equally well with positive muons.

ISSN:0034-6748    

DOI:10.1063/1.1770942

出版商:AIP    

年代:1954

数据来源: AIP

摘要:

An improved electron current and energy regulator for mass spectrometer ion sources is described. The improvements over previous regulator circuits consist of (a) a two kilocycle filament excitation supply which allows improved filament emission control and (b) a method of controlling the filament to shield voltage over a wide range of electron energies. Data on isotope ratio measurements are provided to show the increased stability over that of previous regulators.

ISSN:0034-6748    

DOI:10.1063/1.1770943

出版商:AIP    

年代:1954

数据来源: AIP

摘要:

The problems involved in the construction of a magnetic refrigerator operating below 1°K, using superconducting metallic links for the thermal valves and a paramagnetic salt as the working substance, are discussed. A cycle for the operation of the refrigerator is suggested and then examined for the optimum operating conditions with readily available laboratory facilities. Design equations are obtained and compared with our more recent experimental model. The constructional details of a completely automatic experimental model of the magnetic refrigerator using lead for the thermal valves, iron ammonium alum as the working substance, a helium bath at 1°K as the high‐temperature reservoir, a maximum magnetic field of 7000 gauss, a 2 minute cycle of operation, and capable of extracting 120 ergs/second from a reservoir at 0.3°K are presented in full. Temperatures as low as 0.2°K are obtained with this model. Improvements in this this design, its use either for the production of an isothermal reservoir or as a heat sink for adiabatic demagnetization work below 1°K, and the extension to a two‐engine refrigerator for the production of a reservoir at temperatures as low as 0.05°K are also discussed.

ISSN:0034-6748    

DOI:10.1063/1.1770944

出版商:AIP    

年代:1954

数据来源: AIP

摘要:

An interferometer of the amplitude‐splitting type has been constructed which operates with electron beams and produces a system of fringes in the viewing instrument. The appearance of the fringes may be varied at will by introducing changes in one of the (electron) optical paths. The instrument utilizes crystalline diffraction for beam splitting and recombining.

ISSN:0034-6748    

DOI:10.1063/1.1770945

出版商:AIP    

年代:1954

数据来源: AIP

摘要:

An elementary theory based on light optical analogues is presented. Calculations of fringe orientation are in good agreement with experimental values. The theory leads to a value, based on experimental data, of the coherence length of an electron in excess of 5800 wavelengths.

ISSN:0034-6748    

DOI:10.1063/1.1770946

出版商:AIP    

年代:1954

数据来源: AIP