摘要:

An approximation formula for the solid angle subtended at a point by a right circular cylinder is obtained and its error evaluated. The variation in the solid angle with displacement of the point from the symmetrical plane through the center of the cylinder at right angles to the axis is also discussed.

ISSN:0034-6748    

DOI:10.1063/1.1717302

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

A maser preamplifier designed for radiometry at a wavelength of 21 cm is described. The maser is mounted at the focus of the 60‐ft reflector of the Harvard College Observatory and is being used principally for observations of hydrogen‐line radiation from extra‐galactic nebulae. An automatic gain stabilization system for the maser using a modulated‐noise reference signal is described and an example of an observation made with this stabilization scheme is included. The total input noise temperature of the radiometer is 85°K, without the gain stabilization, and 148°K with the stabilization.

ISSN:0034-6748    

DOI:10.1063/1.1717303

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

The design of a high current transistorized potentiostat capable of delivering currents of the order of 5 amp for anodic or cathodic polarization studies at controlled potentials is presented. The range of potentials possible is determined only by the characteristics of the test electrode/solution interface. The response of this instrument is such that switching from maximum cathodic to maximum anodic potentials and vice versa can be accomplished within 10−3sec. Analysis indicates that it is possible to effect a tenfold increase in the current‐carrying capacity of this potentiostat with only minor modifications. The combination of high speed, short rise time, and high current instantly available for either anodic or cathodic polarization is unique in this potentiostat and provides outstanding versatility.

ISSN:0034-6748    

DOI:10.1063/1.1717304

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

A complete pulsed neutron system has been developed for use in reactor reactivity measurements. The probe unit is small enough to fit into a reactor instrumentation pipe. The pulse‐to‐pulse variation in neutron output has been kept to a minimum by regulating the gas pressure in the neutron tube and by maintaining the same pulsing conditions regardless of pulsing rate. The total neutron output per pulse is in excess of 107neutrons, and the maximum pulsing rate is 10 pulses/sec. The neutron tube has a useful life of 106pulses. The system meets the design requirements; however, some additional work may be necessary if temperatures experienced during actual operation in the reactor affect the pressure regulating system of the tube.

ISSN:0034-6748    

DOI:10.1063/1.1717305

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

A grazing incidence spectrograph, originally designed for photographic registration, is modified for the purpose of making attenuation measurements at selected wavelengths in the 100–300 A region. The modifications over previous procedures include: (1) the introduction of an open multistage Cu‐Be electron multiplier for the purpose of comparing intensities by counting photons; (2) the use of the characteristic valence emission bands of the light metals as sources of incident radiation. The photomultiplier is mounted on an arm attached to a spindle whose axis is normal to the base plate and passes through the Rowland circle at the selected wavelength. Defining slits, placed between the grating and entrance window of photomultiplier, limit the spectral band used in irradiating the absorbers. The latter are placed in the diffracted beam at the position of ``least confusion'' and may be rotated independently about the common vertical axis of the spindle, thus varying the angle at which the incident beam strikes the surface of the sample. Various tests indicate that the source intensity and detector sensitivity are adequate for the attainment of satisfactory counting rates. In conjunction with the particular sources referred to, the photon‐counting scheme makes it possible to improve materially the precision of existing attenuation measurements.

ISSN:0034-6748    

DOI:10.1063/1.1717306

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

The exponential current‐voltage characteristic of the input of a grounded base junction transistor is utilized to construct an analog multiplier. Four‐quadrant operation is obtained by using two channels—one with pnp and the other with npn transistors. Design considerations of the various components of the multiplier are discussed. It is shown that the performance of the multiplier—particularly in respect of bandwidth—compares favorably with that of the other types described in the literature.

ISSN:0034-6748    

DOI:10.1063/1.1717307

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

A scheme of combining a large number of low level output particle detectors into a hodoscope is described. Features include economy of amplification equipment and a short resolving time against accidental events.

ISSN:0034-6748    

DOI:10.1063/1.1717308

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

A new method and device will be described for measuring the density in a vapor stream of any material that will be deposited on a suitable substrate in vacuum. For this purpose a ``nude'' ionization gauge is used. The new ionization method differs from others in that it discriminates between the ions of the vapor and those resulting from the background pressure in the vacuum system. The ionization gauge is placed over a hole in the substrate holder; this hole is periodically opened and closed by a shutter vibrating at a low frequency, so that the ion gauge will receive a pulsed vapor stream and detect an alternating ion current superimposed on the direct ion current. A narrow‐band amplifier will amplify only the alternating ion current of the frequency of the shutter vibrator. A current integrator may control the total amount of evaporated material. The ionization gauge used in this method can easily measure the total pressure when the filtering system is bypassed. Calibration curves will be shown and a theory given. Sensitivities of the order of 1 A/sec and lower have been obtained.

ISSN:0034-6748    

DOI:10.1063/1.1717309

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

The pulse‐height distribution at the output of an electron multiplier structure for a single electron input has been calculated assuming a Poisson distribution at each stage. Graphs are given which illustrate the change in pulse‐height distribution as a function of the number of stages. This has been done for interstage multiplications of 1.5, 2.0, 3.0, and 5.0.

ISSN:0034-6748    

DOI:10.1063/1.1717310

出版商:AIP    

年代:1961

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1717311

出版商:AIP    

年代:1961

数据来源: AIP