摘要:

We describe the design and development of a large format 40‐mm active diameter imaging photon detector. The design comprises an S20 semitransparent photocathode proximity focused onto a stack of two microchannel plates clamped back to back having channel length to diameter ratios of 80:1. Event readout is facilitated by a circular arc terminated resistive anode. The theoretical performance of the design is discussed with reference to gain measurements of the microchannel plates. Experimental results give an optimum position resolution of 100 &mgr;m which is spatially nonuniform and degrades towards the edge of the imaging field. We discuss the role of signal processing in this nonuniformity and describe design modifications which would achieve optimum imaging performance.

ISSN:0034-6748    

DOI:10.1063/1.1139302

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

We have designed and built an improved, dedicated analytical scanning transmission electron microscope (STEM). A novel feature of this microscope is a magnetic lens above the accelerating gun, allowing the specimen probe to achieve very high current densities while retaining the high spatial resolution of the STEM. Integrated with this microscope, we have also implemented an image processing system which allows rapid analysis of the digitized microscope output signals. This processing system also allows the graphic simulation of planar materials (such as intercalated graphite) to derive diffraction pattern simulations for comparison with the experimental data. An image database system allows over 2000 images to be easily managed.

ISSN:0034-6748    

DOI:10.1063/1.1139655

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

A simple apparatus is described which allows the simultaneous microscopic observation of a pattern and the analysis of the light scattered by it at low angles using a single video image. Applications are found any time a spatial Fourier analysis is needed in addition to a simple visualization. As an example, we report a preliminary study of the growth of ‘‘breath figures’’—a pattern formed by the condensation of vapor blown onto a cold surface.

ISSN:0034-6748    

DOI:10.1063/1.1139303

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

A special timing control unit to synchronize the OMA 1205 with a SIT vidicon for a pulsed laser apparatus has been developed. Under special timing conditions the range of linearity of the vidicon response can be enhanced by a factor of 25. The results for the vidicon response as a function of illumination intensity under the realistic conditions of a transient state measurement are presented together with reference data obtained without utilizing the unit. In both cases optimum linearity is achieved with counting rates of about 20 counts/shot only.

ISSN:0034-6748    

DOI:10.1063/1.1139304

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

The distribution of retroreflected light from an array of corner cube prisms is measured as a function of angle of incidence and beam collimation. The imaging properties of the array are compared to those of a plane mirror in the presence and absence of phase perturbations. The implications for the use of a retroreflective array in absorbance measuring instrumentation are discussed.

ISSN:0034-6748    

DOI:10.1063/1.1139305

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

This paper describes a simple and low‐cost electronic device which calculates the position of an incident VUV photon on a commercially available position‐sensitive detector composed of two multichannel plates and a resistive anode. The readout method used consists of a position‐time conversion during data acquisition and a subsequent transformation of the collected data by a personal computer (Apple IIe). Applications to VUV spectrometry in atomic physics, showing spectra of 400 A˚ width with a resolution of about 15 A˚, bring out advantages and drawbacks of this system.

ISSN:0034-6748    

DOI:10.1063/1.1139306

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

A position‐sensitive photodetector is discussed using the transverse photoeffect and a particular geometry in a hydrogenated amorphous silicon (a‐Si:H) junction. A comparison with a more conventional device using the lateral photoeffect ina‐Si:H is made and it is shown that the new device has better characteristics.

ISSN:0034-6748    

DOI:10.1063/1.1139307

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

A translation stage is described which allows rectilinear displacements of up to 200 &mgr;m with a load of 20 N. Lateral deviations from the rectilinear movement do not exceed a few nanometers. Tilts are reduced to a few nanoradians. By means of a piezoelectric drive, slow continuous motion with vibration amplitudes below 0.1 nm is achieved. Residual tilting errors due to machining tolerances and nonideal coupling of the drive are reduced to nrad levels by magnetic compensation elements which are remote controlled.

ISSN:0034-6748    

DOI:10.1063/1.1139308

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

The accuracy of lattice parameter determinations by Read camera x‐ray diffraction is shown to be strongly dependent on camera alignment. Alignment of the Read camera eliminates the main sources of error. Further improvement in analysis was achieved by constructing a collimator with a rectangular cross section. Analysis and testing showed that the rectangular collimator enhances the efficiency, resolution, precision, and peak‐to‐background intensity ratio for x‐ray analysis of thin films using the Read camera.

ISSN:0034-6748    

DOI:10.1063/1.1139309

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

An extension to the 350‐kV negative ion injector for the JAERI tandem accelerator was constructed to minimize loss of the beam time due to changing and tuning the ion sources, and to improve substantially the reliability and personal safety in the accelerator operation. Performance during the first operation over three months is reported and discussed in comparison with the previous performance.

ISSN:0034-6748    

DOI:10.1063/1.1139310

出版商:AIP    

年代:1987

数据来源: AIP