摘要:

A description is given of those features of the University of Minnesota proton linear accelerator which extend the design of the Berkeley linear accelerator. These features are: three separate resonant cavities in series which produce, respectively, beams of 10‐, 40‐, and 68‐Mev protons, as well as appreciable currents when desired at energies between 25 and 68 Mev; a 500‐kv ac injector; a 200‐Mc amplifier system with three isolated output stages producing 0.6, 2.2, and 3.2 Mw of pulsed power; automatic frequency control systems; phase detectors; phase shifters; magnets; shielding and accessory equipment. The characteristics of the output proton beams are described, and a brief statement is made of the experiments being performed.

ISSN:0034-6748    

DOI:10.1063/1.1716229

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

A &pgr;‐&mgr; decay counter has been designed and used to count positive pions in several synchrotron and cyclotron experiments. Utilizing an improved gate generator and coincidence circuit, the detector possesses a very stable efficiency for counting pions in several energy intervals. The detector is readily adaptable to the addition of extra counters to permit the detection of pions in the presence of large backgrounds.

ISSN:0034-6748    

DOI:10.1063/1.1716230

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

Apparatus has been installed in the high‐voltage terminal of the Brookhaven National Laboratory research electrostatic accelerator for production of ion current pulses in the millimicrosecond range by radio‐frequency sweeping of the beam across a limiting aperture between the ion source and acceleration tube. Proton and deuteron pulses with a full width at half‐maximum of about 4.5 millimicroseconds are presently available, with a pulse repetition time of 134 millimicroseconds and an average current of 1–2 microamperes. A simple electrostatic refractor rejects alternate pulses to give one pulse per rf cycle. The following advantages of this method are to be noted: (1) It minimizes the production of background radiations by ions which are not used on the target, (2) The reduced duty factor makes it potentially possible to correspondingly increase the instantaneous intensity during pulses. The usefulness of the system has been demonstrated by the measurement of the delayed deexcitation by &ggr; emission of the first excited state in B10.

ISSN:0034-6748    

DOI:10.1063/1.1716231

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

A description is given of a simple electronic correlator which employs punched‐tape input and visual digital readout. Cold‐cathode counting tubes are used in the arithmetic unit. Several basic design considerations are briefly discussed, and an outline is given of the recent application of the correlator to a problem in meteor physics.

ISSN:0034-6748    

DOI:10.1063/1.1716232

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

A differential microcalorimeter of the Tian‐Calvet type has been designed and constructed. The galvanometers previously employed have been replaced by a dc amplifier, which materially simplified the construction and operation of the instrument. In addition, this allows an electrical analog integrator to be used which gives directly the heat of reaction.Sensitivity of the instrument in the range from 0.01 to 2 cal is such that measurements can be made with a precision of 1% or better. Measurements have been made, under ideal conditions, of 0.002 cal with a standard deviation of 0.1%.

ISSN:0034-6748    

DOI:10.1063/1.1716233

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

To achieve a precision of temperature control in the range 0.01 to 0.0001°K, it usually is necessary to utilize the greatest sensitivity which can be obtained from a simple resistance thermometer bridge. Over the temperature range ofTfrom 1° to 300°K the resistance,R, of different thermometers may vary from one to thousands of ohms, andRmay increase or decrease withT.Sensitivity, |dR/RdT|, may vary more than tenfold. As the dominant limitation upon useful sensitivity is thermal dissipation of thermometer power, design parameters are derived which afford optimum practical sensitivity at the amplifier output per unit thermometer power. Quite unsymmetrical bridges are preferable. Different conditions are preferable for the basically different thermometers, pure metals, and semiconductors.

ISSN:0034-6748    

DOI:10.1063/1.1716234

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

A method is described by which glass capillary leaks with extremely small flow rates can be easily and rapidly produced. The predictability of these leak rates is determined by the resolution of the optical system used in measurement of bore diameter. Data are given which will allow construction of such leaks. A manifold of leaks is described which will introduce gas into a high‐vacuum system at several different fixed leak rates. It contains no moving parts or high vapor pressure material on the high‐vacuum side, yet the leak rates can be manipulated over a wide range. The characteristic features of these leaks are shown to be reasonable in light of well established theory.

ISSN:0034-6748    

DOI:10.1063/1.1716235

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

A blackbody was constructed of graphite which could be inductively heated in an atmosphere of helium to a maximum temperature of 2700°K. This blackbody was used as a source of radiant energy in the calibration of a grating spectroradiometer. The calibration was made over the spectral range of 2600 to 3800 A in the second order, and of 3300 to 7550 A in the first order. The accuracy of the calibrations was estimated to be of the order of 9% in the regions 2600 to 2800 A in the second order, and 7000 to 7550 A in the first order, and of 5% in the regions 2800 to 3800 A in the second order, and 3300 to 7000 A in the first order.

ISSN:0034-6748    

DOI:10.1063/1.1716236

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

A device, based on Archimedes' Principle, and involving the use of a sensitive quartz spiral as a measuring element, has been constructed to permit the rapid measurement of the density of liquid samples. Withn‐butanol‐n‐heptane solutions which we have used for calibration, a precision of 1 in the fourth decimal place has been obtained.

ISSN:0034-6748    

DOI:10.1063/1.1716237

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

A small infrared spectrometer has been built for general use in the chemical laboratory. Employing a rock salt prism with a 40‐ ×50‐mm base, it records the spectra of samples linearly in transmittance or absorbancevswavelength on flat 8‐ ×23½‐inch charts. Its single set of scanning conditions covers the range from 2 to 16 microns in 16 minutes with a resolution of 3 to 4 cm−1at 10 microns and scattered light of less than 1% at 15 microns.

ISSN:0034-6748    

DOI:10.1063/1.1716238

出版商:AIP    

年代:1958

数据来源: AIP