Pub Date : 1989-08-01DOI: 10.1088/0022-3735/22/8/005
T. Ntoutoume, A. Deguin, C. Lapray, A. Briguet
A simple multiprobe NMR system for static magnetic field mapping is described. It uses an array of several (1-10) small RF coils which are spatially displayed in order to facilitate magnetic field analysis. Field plot is automated and details of electronics which control switched acquisitions are given. The shimming of a whole body magnet operating at 0.15 T is performed.
{"title":"Switched multiprobe NMR system for magnetic field mapping","authors":"T. Ntoutoume, A. Deguin, C. Lapray, A. Briguet","doi":"10.1088/0022-3735/22/8/005","DOIUrl":"https://doi.org/10.1088/0022-3735/22/8/005","url":null,"abstract":"A simple multiprobe NMR system for static magnetic field mapping is described. It uses an array of several (1-10) small RF coils which are spatially displayed in order to facilitate magnetic field analysis. Field plot is automated and details of electronics which control switched acquisitions are given. The shimming of a whole body magnet operating at 0.15 T is performed.","PeriodicalId":16791,"journal":{"name":"Journal of Physics E: Scientific Instruments","volume":"20 1","pages":"557-560"},"PeriodicalIF":0.0,"publicationDate":"1989-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72811197","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1989-08-01DOI: 10.1088/0022-3735/22/8/022
G. A. Jackson, J. Gibson, R. Holmes
An ultrasonic flowmeter has been developed which incorporates a single transmitting transducer and lens system producing a diverging ultrasound beam detected by three widely spaced receiving transducers. This enables measurements to be made with three ultrasound paths in pipelines of relatively small diameter. Volume flow rate is evaluated from measurements of the difference in phase angle between the received signals under 'flow' and 'no-flow' conditions. A separate cross-flow ultrasound system is used to correct measurements for variations in sound velocity with temperature. For fully developed turbulent flow, the measured phase differences are linearly related to flow rate as predicted by theoretical analysis of the system. The meter compares the flow rates derived from the phase-angle differences for three paths. Agreement of all flow rates indicates that fully developed turbulent flow exists, as present during calibration, and a weighted mean flow-rate is determined and displayed. In other cases warning is given that a reliable measurement of the flow rate cannot be made.
{"title":"A three-path ultrasonic flowmeter for small-diameter pipelines","authors":"G. A. Jackson, J. Gibson, R. Holmes","doi":"10.1088/0022-3735/22/8/022","DOIUrl":"https://doi.org/10.1088/0022-3735/22/8/022","url":null,"abstract":"An ultrasonic flowmeter has been developed which incorporates a single transmitting transducer and lens system producing a diverging ultrasound beam detected by three widely spaced receiving transducers. This enables measurements to be made with three ultrasound paths in pipelines of relatively small diameter. Volume flow rate is evaluated from measurements of the difference in phase angle between the received signals under 'flow' and 'no-flow' conditions. A separate cross-flow ultrasound system is used to correct measurements for variations in sound velocity with temperature. For fully developed turbulent flow, the measured phase differences are linearly related to flow rate as predicted by theoretical analysis of the system. The meter compares the flow rates derived from the phase-angle differences for three paths. Agreement of all flow rates indicates that fully developed turbulent flow exists, as present during calibration, and a weighted mean flow-rate is determined and displayed. In other cases warning is given that a reliable measurement of the flow rate cannot be made.","PeriodicalId":16791,"journal":{"name":"Journal of Physics E: Scientific Instruments","volume":"104 1","pages":"645-650"},"PeriodicalIF":0.0,"publicationDate":"1989-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80812395","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1989-08-01DOI: 10.1088/0022-3735/22/8/009
S. Edwards, H. B. Rani, J. Wigmore
The authors discuss the use of superconducting edge bolometers for detecting heat pulses in the regime in which pulse lengths are shorter than the bolometer response time. An algorithm is described which enables deconvolution of the observed bolometer signal to give the incident phonon flux. Backscattering data taken on 2 mm sapphire crystals suggest that the method will also be successful in the study of much thinner samples, for example, the 0.5 mm thick wafers used in MBE technology.
{"title":"The use of superconducting bolometers for detecting nanosecond heat pulses","authors":"S. Edwards, H. B. Rani, J. Wigmore","doi":"10.1088/0022-3735/22/8/009","DOIUrl":"https://doi.org/10.1088/0022-3735/22/8/009","url":null,"abstract":"The authors discuss the use of superconducting edge bolometers for detecting heat pulses in the regime in which pulse lengths are shorter than the bolometer response time. An algorithm is described which enables deconvolution of the observed bolometer signal to give the incident phonon flux. Backscattering data taken on 2 mm sapphire crystals suggest that the method will also be successful in the study of much thinner samples, for example, the 0.5 mm thick wafers used in MBE technology.","PeriodicalId":16791,"journal":{"name":"Journal of Physics E: Scientific Instruments","volume":"14 1","pages":"582-586"},"PeriodicalIF":0.0,"publicationDate":"1989-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86699346","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1989-08-01DOI: 10.1088/0022-3735/22/8/011
H. Frei, G. Grathwohl
A four-point bender for high-strength ceramics is described. Its compact design allows it to be incorporated into the mechanical stage of a commercially produced SEM, without the need for external mechanical feedthroughs. Static, dynamic and cyclic bending operations can be carried out by means of an electronically controlled piezoelectric displacement transducer. Simultaneous SEM observation and force measurement by means of a quartz crystal transducers are also provided. Typical results achieved with advanced ceramics as load-displacement curves and observations of the crack propagation paths are included.
{"title":"Development of a piezotranslator-based bending device for in situ SEM investigations of high-performance ceramics","authors":"H. Frei, G. Grathwohl","doi":"10.1088/0022-3735/22/8/011","DOIUrl":"https://doi.org/10.1088/0022-3735/22/8/011","url":null,"abstract":"A four-point bender for high-strength ceramics is described. Its compact design allows it to be incorporated into the mechanical stage of a commercially produced SEM, without the need for external mechanical feedthroughs. Static, dynamic and cyclic bending operations can be carried out by means of an electronically controlled piezoelectric displacement transducer. Simultaneous SEM observation and force measurement by means of a quartz crystal transducers are also provided. Typical results achieved with advanced ceramics as load-displacement curves and observations of the crack propagation paths are included.","PeriodicalId":16791,"journal":{"name":"Journal of Physics E: Scientific Instruments","volume":"12 1","pages":"589-593"},"PeriodicalIF":0.0,"publicationDate":"1989-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86679273","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1989-08-01DOI: 10.1088/0022-3735/22/8/006
H. T. Brake, Z. Dunajski, W.A.G. van der Mheen, J. Flokstra
An electronically balanced three-channel SQUID magnetometer is presented. The electronic balancing reduces the imbalance of the gradiometers by at least a factor of 100. The authors realised in this way an imbalance of 10-5, without the necessity of prebalancing by means of superconducting tabs. Details of the design considerations and the construction of the three-channel system are given, focusing especially on the electronic balancing unit. Some illustrating experiments are also described and the possibilities of electronic balancing discussed
{"title":"Electronic balancing of multichannel SQUID magnetometers","authors":"H. T. Brake, Z. Dunajski, W.A.G. van der Mheen, J. Flokstra","doi":"10.1088/0022-3735/22/8/006","DOIUrl":"https://doi.org/10.1088/0022-3735/22/8/006","url":null,"abstract":"An electronically balanced three-channel SQUID magnetometer is presented. The electronic balancing reduces the imbalance of the gradiometers by at least a factor of 100. The authors realised in this way an imbalance of 10-5, without the necessity of prebalancing by means of superconducting tabs. Details of the design considerations and the construction of the three-channel system are given, focusing especially on the electronic balancing unit. Some illustrating experiments are also described and the possibilities of electronic balancing discussed","PeriodicalId":16791,"journal":{"name":"Journal of Physics E: Scientific Instruments","volume":"12 1","pages":"560-564"},"PeriodicalIF":0.0,"publicationDate":"1989-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79712905","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1989-08-01DOI: 10.1088/0022-3735/22/8/023
R. D. Diehl, S. Chandavarkar
The authors discuss the advantages of using a flat suppressor in low-energy electron diffraction (LEED). A flat-suppressor system which incorporates a channel electron multiplier plate and a phosphor screen detector is described. The LEED patterns can be analysed using standard lineshape fitting programs. Preliminary results from experiments on the hexagonal incommensurate phase of potassium chemisorbed on Ni(111) are presented.
{"title":"The use of a flat suppressor in low-energy electron diffraction","authors":"R. D. Diehl, S. Chandavarkar","doi":"10.1088/0022-3735/22/8/023","DOIUrl":"https://doi.org/10.1088/0022-3735/22/8/023","url":null,"abstract":"The authors discuss the advantages of using a flat suppressor in low-energy electron diffraction (LEED). A flat-suppressor system which incorporates a channel electron multiplier plate and a phosphor screen detector is described. The LEED patterns can be analysed using standard lineshape fitting programs. Preliminary results from experiments on the hexagonal incommensurate phase of potassium chemisorbed on Ni(111) are presented.","PeriodicalId":16791,"journal":{"name":"Journal of Physics E: Scientific Instruments","volume":"91 1","pages":"651-656"},"PeriodicalIF":0.0,"publicationDate":"1989-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84023516","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1989-08-01DOI: 10.1088/0022-3735/22/8/004
F. Mitchell, A. Alwis
A description is given of a cell and associated electronic unit suitable for the measurement of the electrical conductivity of foods. Some measured conductivities are reported.
描述了一种适用于测量食品电导率的电池和相关电子单元。报道了一些测量的电导率。
{"title":"Electrical conductivity meter for food samples","authors":"F. Mitchell, A. Alwis","doi":"10.1088/0022-3735/22/8/004","DOIUrl":"https://doi.org/10.1088/0022-3735/22/8/004","url":null,"abstract":"A description is given of a cell and associated electronic unit suitable for the measurement of the electrical conductivity of foods. Some measured conductivities are reported.","PeriodicalId":16791,"journal":{"name":"Journal of Physics E: Scientific Instruments","volume":"76 1","pages":"554-556"},"PeriodicalIF":0.0,"publicationDate":"1989-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88091163","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1989-08-01DOI: 10.1088/0022-3735/22/8/020
D. Matovic, C. Tropea
The autocovariance (ACV) lag ratio method of determining the frequency of single realisation LDA signals is introduced and examined in detail. Properties of this method and of the frequency estimator are derived analytically and verified using numerical simulation. The simulation is also used to investigate the performance of the estimator in terms of digitising parameters and to compare the results with an estimate based on the power spectral density. The ACV lag ratio method has been implemented experimentally using a transient recorder to digitise the Doppler signals and an optimised software routine to apply the method. Results from simulated and real Doppler signals show that the ACV lag ratio method maintains high accuracy over a wide effective bandwidth and is robust to the choice of digitising parameters.
{"title":"Estimation of LDA signal frequency using the autocovariance (ACV) lag ratio method","authors":"D. Matovic, C. Tropea","doi":"10.1088/0022-3735/22/8/020","DOIUrl":"https://doi.org/10.1088/0022-3735/22/8/020","url":null,"abstract":"The autocovariance (ACV) lag ratio method of determining the frequency of single realisation LDA signals is introduced and examined in detail. Properties of this method and of the frequency estimator are derived analytically and verified using numerical simulation. The simulation is also used to investigate the performance of the estimator in terms of digitising parameters and to compare the results with an estimate based on the power spectral density. The ACV lag ratio method has been implemented experimentally using a transient recorder to digitise the Doppler signals and an optimised software routine to apply the method. Results from simulated and real Doppler signals show that the ACV lag ratio method maintains high accuracy over a wide effective bandwidth and is robust to the choice of digitising parameters.","PeriodicalId":16791,"journal":{"name":"Journal of Physics E: Scientific Instruments","volume":"76 1","pages":"631-637"},"PeriodicalIF":0.0,"publicationDate":"1989-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83829726","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1989-08-01DOI: 10.1088/0022-3735/22/8/008
S. Pittard, M. Fry, R. Ellis, E. Moore, W. Vennart
The design, construction and performance of a low-cost magnetic resonance imaging (MRI) system is described. The system uses a unique, PC-based, task-oriented multiprocessor design, resulting in a high-performance MRI system able to run most pulse sequences. This type of design could lead to a new generation of low-cost MRI systems with applications in research and teaching.
{"title":"A low-cost magnetic resonance imaging system","authors":"S. Pittard, M. Fry, R. Ellis, E. Moore, W. Vennart","doi":"10.1088/0022-3735/22/8/008","DOIUrl":"https://doi.org/10.1088/0022-3735/22/8/008","url":null,"abstract":"The design, construction and performance of a low-cost magnetic resonance imaging (MRI) system is described. The system uses a unique, PC-based, task-oriented multiprocessor design, resulting in a high-performance MRI system able to run most pulse sequences. This type of design could lead to a new generation of low-cost MRI systems with applications in research and teaching.","PeriodicalId":16791,"journal":{"name":"Journal of Physics E: Scientific Instruments","volume":"10 1","pages":"574-582"},"PeriodicalIF":0.0,"publicationDate":"1989-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88111464","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1989-08-01DOI: 10.1088/0022-3735/22/8/013
A. Entwistle, C. Dyer, J. Quenby, A. Evans, M. Joshi
Particle-induced background in germanium spectrometers used for astrophysical and remote sensing measurement in a space environment provides an important limitation to the ultimate instrument sensitivity. To aid future experimental design and interpretation, laboratory exposure of typical sensors to known fluences of slow and fast neutrons and energetic protons is carried out to predict the line and continuum background components. Fast neutron elastic scatter is found to be the chief source of background below 100 keV for an unshielded detector inside a heavy spacecraft. At higher energies, comparable contributions are identified from neutron inelastic scattering and neutron- and proton-induced radioactivity. Radiation damage to an n-type high purity Ge detector caused broadening in resolution by a factor of 1.8 after subjection to 1.2*1010 protons of 600 MeV.
{"title":"Measurement of neutron and proton-induced background in germanium gamma-ray spectrometers for use in a space environment","authors":"A. Entwistle, C. Dyer, J. Quenby, A. Evans, M. Joshi","doi":"10.1088/0022-3735/22/8/013","DOIUrl":"https://doi.org/10.1088/0022-3735/22/8/013","url":null,"abstract":"Particle-induced background in germanium spectrometers used for astrophysical and remote sensing measurement in a space environment provides an important limitation to the ultimate instrument sensitivity. To aid future experimental design and interpretation, laboratory exposure of typical sensors to known fluences of slow and fast neutrons and energetic protons is carried out to predict the line and continuum background components. Fast neutron elastic scatter is found to be the chief source of background below 100 keV for an unshielded detector inside a heavy spacecraft. At higher energies, comparable contributions are identified from neutron inelastic scattering and neutron- and proton-induced radioactivity. Radiation damage to an n-type high purity Ge detector caused broadening in resolution by a factor of 1.8 after subjection to 1.2*1010 protons of 600 MeV.","PeriodicalId":16791,"journal":{"name":"Journal of Physics E: Scientific Instruments","volume":"55 1","pages":"601-611"},"PeriodicalIF":0.0,"publicationDate":"1989-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79648666","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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