High-Resolution Strain Mapping Through Time-of-Flight Neutron Transmission Diffraction

2013 ◽  
Vol 772 ◽  
pp. 9-13 ◽  
Author(s):  
Anton S. Tremsin ◽  
Jason B. McPhate ◽  
John V. Vallerga ◽  
Oswald H.W. Siegmund ◽  
Winfried Kockelmann ◽  
...  
Keyword(s):  
High Resolution ◽  
Spatial Resolution ◽  
Time Of Flight ◽  
Compact Tension ◽  
Strain Mapping ◽  
Neutron Transmission ◽  
Neutron Counting ◽  
Transmission Measurements ◽  
Pulsed Neutron ◽  
Pulsed Neutron Source

The spatial resolution of time of flight neutron transmission diffraction was recently improved by the extension of photon/electron counting technology to imaging of thermal and cold neutrons. The development of novel neutron sensitive microchannel plates enables neutron counting with spatial resolution of ~55 um and time-of-flight accuracy of ~1 us, with efficiency as high as 70% for cold and ~40% for thermal neutrons. The combination of such a high resolution detector with a pulsed collimated neuron beam provides the opportunity to obtain a 2-dimensional map of neutron transmission spectra in one measurement. The results of our neuron transmission measurements demonstrate that maps of strains integrated along the beam propagation direction can be obtained with ~100 microstrain accuracy and spatial resolution of ~100 um providing there are sufficient neutron events collected. In this paper we describe the capabilities of the MCP neutron counting detectors and present the experimental results of 2-dimensional strain maps within austenitic steel compact tension (CT) crack samples measured at the ENGIN-X beamline of the ISIS pulsed neutron source.

High-Resolution Strain Mapping Through Time-of-Flight Neutron Transmission Diffraction with a Microchannel Plate Neutron Counting Detector

Strain ◽  
2011 ◽  
Vol 48 (4) ◽  
pp. 296-305 ◽  
Author(s):  
A. S. Tremsin ◽  
J. B. McPhate ◽  
A. Steuwer ◽  
W. Kockelmann ◽  
A. M Paradowska ◽  
...  
Keyword(s):  
High Resolution ◽  
Time Of Flight ◽  
Microchannel Plate ◽  
Strain Mapping ◽  
Neutron Transmission ◽  
Neutron Counting

Electronically focused time-of-flight powder diffractometers at the intense pulsed neutron source

1989 ◽  
Vol 22 (4) ◽  
pp. 321-333 ◽  
Author(s):  
J. D. Jorgensen ◽  
J. Faber ◽  
J. M. Carpenter ◽  
R. K. Crawford ◽  
J. R. Haumann ◽  
...  
Keyword(s):  
High Resolution ◽  
Neutron Source ◽  
Rietveld Method ◽  
Time Of Flight ◽  
Scattering Angle ◽  
Wide Range ◽  
Pulsed Neutron ◽  
Pulsed Neutron Source

Two time-of-flight powder diffractometers have operated at the Intense Pulsed Neutron Source (IPNS) since August 1981. These instruments use dedicated microcomputers to focus time-of-flight events so that data from different detectors can be summed into a single histogram. Thus, large multidetector arrays can be employed at any scattering angle from 12 to 157°. This design permits data to be collected over a uniquely wide range of d spacings while maintaining high resolution and count rates. The performance of the two instruments is evaluated by analyzing data from a standard Al2O3 sample by the Rietveld method. These instruments provide the capability for moderate- to high-resolution measurements with the duration of a typical run being a few hours.

Energy-Resolving Neutron Transmission Radiography at the ISIS Pulsed Spallation Source With a High-Resolution Neutron Counting Detector

2009 ◽  
Vol 56 (5) ◽  
pp. 2931-2937 ◽  
Author(s):  
Anton S. Tremsin ◽  
Jason B. McPhate ◽  
Winfried A. Kockelmann ◽  
John V. Vallerga ◽  
Oswald H. W. Siegmund ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
Strain Analysis ◽  
Radiographic Image ◽  
Neutron Transmission ◽  
Neutron Sources ◽  
Spatially Correlated ◽  
Neutron Counting ◽  
Spallation Source ◽  
Pulsed Neutron ◽  
Energy Information

Neutron transmission radiography can be strongly enhanced by adding spectroscopic data spatially correlated with the attenuation coefficient. This can now be achieved at pulsed neutron sources, utilizing a neutron detector with high spatial and temporal resolution. The energy of transmitted neutrons can be recovered from their time-of-flight, simultaneously with the acquisition of the transmission radiographic image by a pixelated detector. From this, the positions of Bragg edges can be obtained for each pixel of the radiographic image. The combination of both spectroscopic and transmission information enables high spatial resolution studies to be carried out on material composition, phase transitions, texture variations, as well as strain analysis, as long as the resolution and statistics are favorable. This paper presents initial results from proof-of-principle experiments on energy-resolved neutron transmission radiography, using a neutron counting detector consisting of neutron-sensitive microchannel plates (MCPs) and a Medipix2 electronic readout. These experiments demonstrate that the position of Bragg edges are measurable with a few mAring resolution in each 55-mum pixel of the detector, corresponding to DeltaE/E~0.1%. However, the limited intensity of most current neutron sources requires a compromise between the energy resolution and the area over which it was integrated. Still, the latter limitation can be overcome by combining energy information for several neighboring pixels, while transmission radiography can still be done at the limit of the detector spatial resolution.

Resolution of time-of-flight small-angle neutron diffractometers

1987 ◽  
Vol 20 (4) ◽  
pp. 273-279 ◽  
Author(s):  
R. P. Hjelm
Keyword(s):  
Small Angle ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
Time Of Flight ◽  
Simple Method ◽  
Neutron Diffractometer ◽  
Reduction Methods ◽  
Measurement Strategies ◽  
Pulsed Neutron ◽  
Pulsed Neutron Source

A simple method of calculating the resolution of small-angle neutron data from diffractometers which use time-of-flight techniques has been derived in terms of the variances of the time and spatial channels of the measurement. The method is used to calculate the resolution in scattering-vector space of scattering intensity from a simulated isotropic scatterer on the small-angle neutron diffractometer at the Intense Pulsed Neutron Source at Argonne National Laboratory. The effects of the various instrumental geometries, time-of-flight measurement strategies and data reduction methods that can be chosen by the experimenter are considered. It is found that the best resolution is obtained with weighted constant Δt/t time-of-flight data acquisition schemes, with the detector placed in the beam in such a way that the highest possible angular range is accessed.

A high resolution neutron counting sensors in strain mapping through a transmission bragg edge diffraction

2010 ◽  
Author(s):  
A S Tremsin ◽  
J B McPhate ◽  
J V Vallerga ◽  
O H W Siegmund ◽  
A Steuwer ◽  
...  
Keyword(s):  
High Resolution ◽  
Strain Mapping ◽  
Edge Diffraction ◽  
Neutron Counting
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