摘要:

This report discusses the design and performance of the Bausch and Lomb 33–84–91 densitometer. Fundamental requirements of design are stated and construction is described on the basis of these requirements. Performance data of the instrument are discussed in detail and records are given to demonstrate its fidelity of reproduction.

ISSN:0034-6748    

DOI:10.1063/1.1745913

出版商:AIP    

年代:1951

数据来源: AIP

摘要:

Scattering losses in various electron and proton synchrotrons by residual gas molecules are obtained for a variety of conditions. Evaluation is made of the effects of (1) injection energy of the particles, (2) the spread of the injected beam, (3) the pressure of the residual gas, (4) the rate at which energy is supplied to the beam particles, and (5) the aperture of the accelerator. It is shown that multiple scattering is the really important factor and that losses due to single scattering are of relative importance only when the total effect of single and multiple scattering is rather small.Scattering losses are tabulated and estimates made of the residual gas pressures in synchrotrons which will not produce prohibitively large losses.

ISSN:0034-6748    

DOI:10.1063/1.1745914

出版商:AIP    

年代:1951

数据来源: AIP

摘要:

An rf system is described which allows the acceleration of either 190‐Mev deuterons or 350‐Mev protons in the Berkeley 184‐inch cyclotron. The dee is connected to a large cross‐section line, which is in turn connected, through a rotating condenser, to a short section of grounded line of approximately the same cross section. At the upper frequency limit of 23.2 megacycles the dee and dee stem oscillate as a half wave line, while the grounded line, which is about one‐quarter wave long, oscillates in the opposite phase. At the low frequency limit of 9.5 megacycles, the whole system looks like a quarter wave line. The oscillator which feeds the system is described.

ISSN:0034-6748    

DOI:10.1063/1.1745915

出版商:AIP    

年代:1951

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1745917

出版商:AIP    

年代:1951

数据来源: AIP

摘要:

The emergent beam from the cyclotron has been focused to bombard targets placed in an evacuated chamber behind shielding walls. Heavy charged particle products from the targets can be counted and identified as to charge and mass by three proportional ionization chambers in time coincidence, utilizing the difference in specific ionization near the end of the particle range. Energy spectra at fixed angles are observed with an automatic foil changer which interposes aluminum absorbers between target and detector. Angular distributions can be studied by rotating the detector about the target with a remote‐controlled selsyn drive. Rapid automatic recording of data is accomplished with count storage circuits, a beam current integrator, mechanisms for scanning through a preselected set of absorber foils, and a pen‐recorder.Reactions studied to date include (d,p), (d,t), (d,&agr;), (p,d), and elastic and inelastic scattering of protons, deuterons, and &agr;‐particles. Targets throughout the periodic table have been used, with special emphasis on the elements available in thin foil form. Research papers published in thePhysical Reviewwill present some of the results obtained to date and describe certain correlations observed.

ISSN:0034-6748    

DOI:10.1063/1.1745918

出版商:AIP    

年代:1951

数据来源: AIP

摘要:

Evidence is given for the presence of negative hydrogen ions in the synchrocyclotron. They are lost by charge neutralization before they reach an energy of about 3 Mev. Protons have been made to circulate in the cyclotron without acceleration after they have reached an energy of 5 to 22 Mev and are found to be lost with a half‐life of ⅓ to 2 seconds.

ISSN:0034-6748    

DOI:10.1063/1.1745919

出版商:AIP    

年代:1951

数据来源: AIP

摘要:

Using organic crystals or liquids as scintillators and 1P21 photomultipliers as detectors, a delayed coincidence circuit has been designed for measuring nuclear lifetimes in the region 10−10−10−7sec. The pulses from the photomultipliers were amplified in distributed amplifiers and applied to a germanium diode bridge coincidence circuit.The apparatus has been used for measuring scintillation decay times, the lifetimes of nuclear transitions, and the time of flight of light over distances of the order of one meter.

ISSN:0034-6748    

DOI:10.1063/1.1745920

出版商:AIP    

年代:1951

数据来源: AIP

摘要:

In a standard molecular beam source the maximum attainable intensity in the collimated beam is limited first by the effusion rate through the oven slit, which must be made sufficiently narrow to attain free molecule flow, and second by unfavorable geometrical factors encountered in selecting a collimated beam from random initial velocities. This paper will propose that the first slit be placed in the flow from a miniature high velocity nozzle coaxial with the final beam. The nozzle converts part (∼¾ for a Mach number of 4 in the design for air to be presented) of the random translational and internal energy of the oven gas into directed mass motion. The mass motion provides an initial rough collimation, which improves both the effusion rate and the geometrical factors, indicating a considerable possible beam intensification (by a factor of ∼75 in the sample design). The velocities of the molecules in the final beam are grouped about the initial mass velocity which provides a partial velocity selection.In this paper a theoretical design study and estimates of performance of this type of source are given.

ISSN:0034-6748    

DOI:10.1063/1.1745921

出版商:AIP    

年代:1951

数据来源: AIP

摘要:

The ordinary effusion (``oven'') slit of a conventional molecular beam apparatus was replaced by a slit of special design facing into a supersonic jet from a miniature nozzle. Using ammonia as a test gas, it was observed that at inlet pressures above about 170 mm the molecular beam intensity began to rise far more rapidly than the pressure. The maximum observed intensity exceeded by more than a factor of twenty that obtainable from the effusion slits under optimum conditions and continued to rise rapidly at the highest inlet pressures possible with the available equipment. Certain imperfections of the present apparatus restricted observations to ammonia; their presence indicates that still greater enhancement of molecular beam intensity is possible with an apparatus of refined design.

ISSN:0034-6748    

DOI:10.1063/1.1745922

出版商:AIP    

年代:1951

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1745924

出版商:AIP    

年代:1951

数据来源: AIP