scholarly journals Determination of Calcium in Wolframite Concentrates by Fluorescent X-Ray Spectrography

1958 ◽  
Vol 2 ◽  
pp. 313-332 ◽  
Author(s):  
William J. Campbell ◽  
John W. Thatcher
Keyword(s):  
Gas Flow ◽  
Position Effect ◽  
Pulse Height ◽  
Calcium Content ◽  
Accurate Method ◽  
Counting Efficiency ◽  
Matrix Composition ◽  
Operating Characteristics ◽  
X Ray ◽  
Small Depth

AbstractThe purpose of this investigation was to develop a rapid, accurate method of analysis for small amounts of calcium in wolframite concentrates. This analysis is necessary to determine if wolframite concentrates meet the U. S. National Stockpile Specification P-57R2, which limits the calcium content to 0.2 per cent.Because of the small depth of sample analyzed in fluorescent x-ray spectrography the calcium Kα line intensity was found to be a function of the chemical composition of the calcium-bearing particle as well as the matrix composition. This particle-conn position effect was particularly important in this analysis because the calcium may be present as a carbonate, tungstate, phosphate, etc. Three methods of sample preparation were found to eliminate the variation of calcium Kα intensity with mineralogical occurrences: (1) Reduction in particle size by extensive grinding, (2) chemical fusion wtli sodium carbonate, and (3) solution of the calcium by an add.Determinations by all three procedures are believed to be accurate to within ± 5 per cent for more than 0.30 per cent calcium and ± 10 per cent at the 0.1-per cent level. The lower limit of detectability is in the order of 0.005-0.01 per cent.The operating characteristics of a gas-flow proportional counter used in conjunction with a pulse-height analyzer were studied in detail. This detector was found to have a high counting efficiency for calcium Ka radiation, to have a low counting efficiency for overlapping higher order radiation and to have counting stability equivalent to Geiger tubes.

X-ray Detectors: Pulse Height Shifts, Escape Peaks and Counting Losses

1990 ◽  
Vol 34 ◽  
pp. 319-324
Author(s):  
Michael A. Short
Keyword(s):  
Data Processing ◽  
Pulse Height ◽  
Fluorescence Analysis ◽  
Operating Characteristics ◽  
X Ray ◽  
Computer Based ◽  
Computer Controlled ◽  
Computerized Data Processing

With the ever increasing emphasis on computer-controlled hardware, computerized data processing and computer-based display of results, there is a tendency to forget the operating characteristics of some of the older, more mundane, components of X-ray diffractometers and X-ray fluorescence analysis units. We place our trust in the specifications of the components supplied by the equipment manufacturers and, while usually complete, it nevertheless behooves us to be well aware of the operation of the various hardware components of diffractometers and spectrometers.

A New Model of X-Ray Position Sensitive Detector Developed in France

1980 ◽  
Vol 24 ◽  
pp. 139-141 ◽  
Author(s):  
Louis Castex ◽  
Jean Lou Lebrun ◽  
Serge Bras
Keyword(s):  
Gas Flow ◽  
Carbon Film ◽  
Pulse Height ◽  
Carbon Layer ◽  
Standard Equipment ◽  
X Ray ◽  
Pulse Height Analysis ◽  
Thin Carbon ◽  
Position Sensitive ◽  
The One

Since 1973 X-ray position sensitive detectors (P.S.D.) have been employed for stress analysis. The first models, based on the gas flow of Ar-CH4, were composed of a quartz fiber anode (20 um diameter), coated by a thin carbon layer. From 1975 the gas filling has become permanent. Hence the use of fiber P.S.D. (F-P.S.D.) was made easier; nevertheless, two important inconveniences remained. On the one hand, an intensive X-ray beam could destroy rapidly and locally the carbon film, which makes the detector malfunction; on the other hand, the pulse height analysis (P.H.A.), carried out in 1976, has proved to be ineffectual because of the design of the F-P.S.D. itself: its fiber impedance does not remain constant. Thus the appearnace, in 1979, of a new P.S.D. with a metallic wire (W-P.S.D.) presented a significant advantage (see Fig. 1). The anode—made of tungsten or molybdenum Gilded--can resist intensive X-ray beams perfectly. Hence the life of the detector is only limited by a possible ionization of the filling gas, which approximately corresponds to 1012 counts. A gas refilling--which will be provided in the standard equipment--allows us to use the detector again.

Electron Microscopy/Diffraction Study of the Ternary Mn-Er-S System

1990 ◽  
Vol 48 (1) ◽  
pp. 76-77
Author(s):  
A. R. Landa Canovas ◽  
L.C. Otero Diaz ◽  
T. White ◽  
B.G. Hyde
Keyword(s):  
Electron Microscopy ◽  
Gas Flow ◽  
Graphite Crucible ◽  
Nominal Composition ◽  
X Ray Diffraction ◽  
Alumina Crucible ◽  
X Ray ◽  
Intermediate Phases ◽  
Twin Band ◽  
Ar Gas

X-Ray diffraction revealed two intermediate phases in the system MnS+Er2S3,:MnEr2S4= MnS.Er2S3, and MnEr4S7= MnS.2Er2S3. Their structures may be described as NaCl type, chemically twinned at the unit cell level, and isostructural with CaTi2O4, and Y5S7 respectively; i.e. {l13} NaCl twin band widths are (4,4) and (4,3).The present study was to search for structurally-related (twinned B.) structures and or possible disorder, using the more sensitive and appropiate technigue of electron microscopy/diffraction.A sample with nominal composition MnEr2S4 was made by heating Mn3O4 and Er2O3 in a graphite crucible and a 5% H2S in Ar gas flow at 1500°C for 4 hours. A small amount of this material was thenannealed, in an alumina crucible, contained in sealed evacuated silica tube, for 24 days at 1100°C. Both samples were studied by X-ray powder diffraction, and in JEOL 2000 FX and 4000 EX microscopes.

Energy-dependent dead-time correction in digital pulse processors applied to silicon drift detector's X-ray spectra

2018 ◽  
Vol 25 (2) ◽  
pp. 484-495 ◽  
Author(s):  
Suelen F. Barros ◽  
Vito R. Vanin ◽  
Alexandre A. Malafronte ◽  
Nora L. Maidana ◽  
Marcos N. Martins
Keyword(s):  
Dead Time ◽  
Pulse Height ◽  
Height Distribution ◽  
Pulse Height Distribution ◽  
Dead Time Correction ◽  
Time Model ◽  
X Ray ◽  
Digital Pulse ◽  
Analytical Correction ◽  
Energy Dependent

Dead-time effects in X-ray spectra taken with a digital pulse processor and a silicon drift detector were investigated when the number of events at the low-energy end of the spectrum was more than half of the total, at counting rates up to 56 kHz. It was found that dead-time losses in the spectra are energy dependent and an analytical correction for this effect, which takes into account pulse pile-up, is proposed. This and the usual models have been applied to experimental measurements, evaluating the dead-time fraction either from the calculations or using the value given by the detector acquisition system. The energy-dependent dead-time model proposed fits accurately the experimental energy spectra in the range of counting rates explored in this work. A selection chart of the simplest mathematical model able to correct the pulse-height distribution according to counting rate and energy spectrum characteristics is included.

Development of Gas Scintillation Proportional Counter

1999 ◽  
Vol 09 (03n04) ◽  
pp. 169-174
Author(s):  
N. Shigeoka ◽  
K. Mutaguchi ◽  
Y. Nakanishi ◽  
Y. Ito ◽  
T. Mukoyama ◽  
...  
Keyword(s):  
Proportional Counter ◽  
Pulse Height ◽  
Acceleration Region ◽  
X Ray ◽  
Gaussian Profile ◽  
Profile Fitting ◽  
Fitting Method

The properties of gas scintillation proportional counter are investigated for Mn K x-ray spectra. The pulse-height spectra are strongly affected by changing of the value of a potential V 2 in the acceleration region and analyzed by the Gaussian profile fitting method.

scholarly journals In-situ diffraction experiments at the Photon Factory MX beamlines

2014 ◽  
Vol 70 (a1) ◽  
pp. C500-C500
Author(s):  
Yusuke Yamada ◽  
Naohiro Matsugaki ◽  
Masahiko Hiraki ◽  
Ryuichi Kato ◽  
Toshiya Senda
Keyword(s):  
Gas Flow ◽  
Active Area ◽  
Array Detector ◽  
Data Sets ◽  
Diffraction Experiment ◽  
X Ray ◽  
Photon Factory ◽  
Large Active Area ◽  
In Situ Diffraction

Crystallization trial is one of the most important but time-consuming steps in macromolecular crystallography. Once a crystal appears in a certain crystallization condition, the crystal is typically harvested from the crystallization drop, soaked into a cryoprotection buffer, flash-cooled with a liquid nitrogen or cold gas flow and finally evaluated its diffraction quality by an X-ray beam. During these long process, crystal may be damaged and the result from the diffraction experiment does not necessarily reflect a nature of the crystal. On in-situ diffraction experiment, where a crystal in a crystallization drop is directly irradiated to an X-ray beam, a diffraction image from a crystal without any external factors such as harvesting and cryoprotection and, as a result, a nature of crystal can be evaluated quickly. In the Photon Factory, a new table-top diffractometer for in-situ diffraction experiments has been developed. It consists of XYZ translation stages with a plate handler, on-axis viewing system with a large numeric aperture and a plate rack where ten crystallization plates can be placed. These components sit on a common plate and it is placed on the existing diffractometer table in the beamline endstation. The CCD detector with a large active area and a pixel array detector with a small active area are used for acquiring diffraction images from crystals. Dedicated control software and user interface were also developed. Since 2014, user operation of the new diffractometer was started and in-situ diffraction experiments were mainly performed for evaluations of crystallization plates from a large crystallization screening project in our facility. BL-17A [1], one of micro-focus beamlines at the Photon Factory, is planned to be upgraded in March 2015. With this upgrade, a new diffractometer, which has a capability to handle a crystallization plate, will be installed so that diffraction data sets from crystals in crystallization drop can be collected.

Behaviour of adult hamsters subjected to hypergravity

1999 ◽  
Vol 9 (1) ◽  
pp. 13-18
Author(s):  
H.N.P.M. Sondag ◽  
H.A.A. de Jong ◽  
W.J. Oosterveld
Keyword(s):  
Sensory Input ◽  
Normal Gravity ◽  
Vestibular Function ◽  
Calcium Content ◽  
Light Conditions ◽  
Altered Gravity ◽  
Normal Functioning ◽  
X Ray ◽  
Small Tube ◽  
Righting Reflex

We studied vestibular function in 20 adult hamsters (3 months old) subjected to either prolonged hypergravity (n=10) or normal gravity (n=10) for 2 months. Locomotion and swimming of the hypergravity hamsters under light conditions were normal. Equilibrium maintenance was severely disturbed; only 6 of 10 hypergravity hamsters managed to walk on the small tube after 2 months, whereas all 10 controls were able to walk on the tube. The air-righting reflex was severely disturbed; the hypergravity hamsters made 30% correct responses. Finally, 5 of 8 hypergravity hamsters had to be saved from drowning when swimming in total darkness. Histological examination of the utricular otoconial layers afterwards, using energy dispersive X-ray element (EDAX) analysis and scanning electron microscopy, did not reveal any differences in calcium content, shape and size distribution of the otoconia between hypergravity hamsters and controls. We suggest that adult hamsters adapt to hypergravity, leading to problems in normal functioning when tested in 1 G, especially in tasks in which sensory input of the vestibular system is important for spatial orientation. These disturbances were more severe in adult hamsters than in young ones, tested in previous experiments. Therefore, we assume that age is a factor for adaptation to altered gravity conditions.

A new soft x-ray pulse height analysis array in the HL-2A tokamak

2009 ◽  
Vol 80 (12) ◽  
pp. 126104 ◽  
Author(s):  
Y. P. Zhang ◽  
Yi Liu ◽  
J. W. Yang ◽  
X. Y. Song ◽  
M. Liao ◽  
...  
Keyword(s):  
Pulse Height ◽  
X Ray ◽  
Pulse Height Analysis
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