摘要:

A two‐dimensional analyzer classifies a coincidence event between two detectors according to both pulse amplitudes. The events are sorted into ``channels'' covering a plane instead of the linear array of a conventional analyzer. For coincidence measurements in which the amplitude spectrum from one detector is examined as a function of the pulse height from the other over a wide range, such a device provides maximum efficiency in recording the data. An analyzer is described, in which each coincidence is recorded on a punched paper tape memory as a pair of correlated numbers (the two pulse heights) in binary notation (1–127). In the subsequent read‐out these two numbers specify a two‐dimensional channel. To examine the information in a particular region of the plane, a circuit controlled by a mechanical tape reader determines those events for which one coordinate lies in a preselected range. The corresponding coordinates are then displayed as a spectrum on a conventional 100‐channel analyzer by a digital‐to‐analog conversion system in such a way that each event appears in the channel whose number is punched on the tape. The maximum recording rate is 8/sec; read‐out is at 10/sec. The maximum number of channels is (127)2. In experiments with low coincidence rates the time taken to record and analyze such data is very considerably less than by conventional methods. Examples are given of the application of the analyzer to a (p,p′&ggr;) experiment and to the identification of energetic charged particles by measuring simultaneously their energy and differential energy loss.

ISSN:0034-6748    

DOI:10.1063/1.1716147

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

A new type of accelerator target has been used to determine the yield of He6from high‐energy nuclear reactions. In this target the nuclear recoil of the product isotope separates it from the target material and carries it into a ``catcher'' gas which is then swept into a counter. Because of the design principle employed in this target, the data can be translated directly into absolute cross sections without explicit knowledge of the recoil properties of the product. This type of system may also prove useful in the determination of (1) the relative stopping powers of gases, (2) the rate of thermal diffusion of product species through the target material, and (3) the chemical properties of short‐lived species of large kinetic energy.

ISSN:0034-6748    

DOI:10.1063/1.1716148

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

A phase oscillation damping system has been developed and successfully tested at the Brookhaven cosmotron. Phase differences between the induced voltage in the beam pickup plates and the rf accelerating voltage are detected and fed back to the frequency control system. The frequency of the rf accelerating voltage is thus adjusted to provide a phase restoring force. The usual 50% beam loss during the accelerating cycle is eliminated and tests indicate that the beam stability with respect to disturbances in fieldvsfrequency characteristic is improved by a factor of five.

ISSN:0034-6748    

DOI:10.1063/1.1716149

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

The design, development, and calibration of a small barium titanate pressure transducer for aerodynamic or acoustic pressure measurements is described. The calibration was carried out in a shock tube. A few typical oscilloscope records of the transducer response to shock waves are shown. From the calibration, it was found that the transducer response is uniform from approximately 5 to 50 000 cps and the sensitivity of the transducer is 0.88×10−6v/dyne/cm2.

ISSN:0034-6748    

DOI:10.1063/1.1716150

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

A simple, inexpensive current regulator has been built using power transistors and a chopper amplifier to regulate magnet currents to <0.001%. Thus far, the regulator has been used to 20 amp and 40 v, and at ∼100 amp and ∼200 v. With minor modifications, it will give very much better regulation.

ISSN:0034-6748    

DOI:10.1063/1.1716151

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

This paper discusses the use of a Mach‐Zehnder interferometer in a study of heat transfer in water. A derivation of the formula is given relating temperature change to fringe shift and a correction procedure is shown for end effects. Temperature distributions are determined for pulse‐heated Nichrome foils in water. With the experimental conditions used in this report, a maximum temperature gradient of 280°C/cm was observed.

ISSN:0034-6748    

DOI:10.1063/1.1716152

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

Part I describes how a capacitor microphone acts as the variable capacitance to modulate the frequency in the tank circuit of an FM transmitter. When ``chopped'' light falls on the capacitor microphone, the capacitance of the microphone fluctuates at the same frequency as the ``chopping'' frequency. In Part II is given an analysis of the action. This shows that absorption of the incident electromagnetic radiation sets up a temperature gradient across the thickness of the front electrode. As a result of this, the front of the electrode, the part facing the radiation source, expands toward the source. This causes a change in the distance between the electrodes of the capacitor and thus varies the capacitance of the microphone. The instrument, which responds to a wide range of frequencies and to a very large dynamic range of intensity, is quite rugged. It has an additional advantage in being its own telemetering device.

ISSN:0034-6748    

DOI:10.1063/1.1716153

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

A solenoid operated needle valve is described which gives smooth and rapid control of gas flow rates over a wide range from a cut‐off value of approximately 10−4micron‐liter sec−1. In conjunction with a suitable pressure transducer the valve may be used for the automatic control of pressure in vacuum systems.

ISSN:0034-6748    

DOI:10.1063/1.1716154

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

The operational amplifier which serves as the basic element of modern electronic differential analyzers is utilized in the precise measurement of the low‐frequency parameters of transistors. The method is based on the current‐controlling and current‐measuring functions which may be performed by the amplifiers.

ISSN:0034-6748    

DOI:10.1063/1.1716155

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

A microphone is described that can be encased in a small‐bore plastic catheter. The small size permits insertion directly into the heart and the precise localization of the origin of heart sounds.The unit uses a two‐section piezoelectric ceramic, operated in a bender mode. The frequency response is flat up to 3000 cps.The sensitivity over the flat frequency range is −124 db referred to 1 v/&mgr;bar.

ISSN:0034-6748    

DOI:10.1063/1.1716156

出版商:AIP    

年代:1958

数据来源: AIP