Neutron Collimation with Microchannel Plates: Calibration of Existing Technology and near Future Possibilities

Tremsin, A.S.; Downing, R. G.; Mildner, D.F.R.; Feller, W.B.; Hussey, D.S.; Jacobson, D.L.; Siegmund, O.H.W.; Arif, M.

doi:10.1109/nssmic.2005.1596220

Cited by 2 publications

(3 citation statements)

References 12 publications

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“…Obviously, at a short distance to the active area the beam divergence does not substantially blur the detected image and therefore we should not expect an improvement of the spatial resolution by a neutron collimator. However, it is important to show that the presence of our compact collimator does not introduce image distortions, as it was predicted by our modelling [9,10]. Figure 4 shows the transmission radiographies of the test mask obtained with the collimator in the beam and without it.…”

Section: Resultsmentioning

confidence: 55%

“…To fully utilize the recent progress in detection systems enabling spatial resolution on a sub-15 µm scale [6]- [8] both high collimation and high intensity beams are required if reasonable image acquisition times are to be realized. Very compact (few mm thick) and efficient (as narrow as ±0.05 degree) neutron polycapillary collimators [9,10] can be a very attractive alternative to the single input aperture or Soller type collimator approaches and in some cases can substantially increase the neutron flux for a given beam divergence. It is achieved by beam collimation by millions of highly parallel pores with diameters on the scale of <10 µm, which match the achievable detector spatial resolution, and thus do not introduce image distortions [9,10].…”

Section: Introductionmentioning

confidence: 99%

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High resolution neutron radiography with very compact and efficient neutron collimators

et al. 2011

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The spatial resolution in neutron imaging is often limited by the neutron beam divergence, especially in experiments where the distance between the sample and the detector cannot be very small. Imaging of relatively large or extended objects or tomographic experiments, where samples have to be rotated, typically require several to tens of centimeters distance between the sample and the detector. Moreover, some neutron imaging techniques require placement of components between the sample and the detector, as in the case of magnetic field imaging with polarized neutrons. Compact and efficient policapillary collimators can be an attractive alternative to the conventionally used beam limiting aperture approach. The possible improvement of spatial resolution by a policapillary collimator is studied in experiments where beam divergence limits the quality of neutron transmission imaging. A ∼7 mm thick collimator with ∼6 µm capillaries demonstrates the possibility to decrease the neutron beam divergence and to diminish the image blurring. The improvement of out-of-angle neutron rejection and peak transmission of our future collimators will be crucial for their effective application in neutron imaging experiments.

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Section: Resultsmentioning

confidence: 55%

Section: Introductionmentioning

confidence: 99%

High resolution neutron radiography with very compact and efficient neutron collimators

et al. 2011

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“…As a more angle-specific option for the shielding, microchannel plates have shown favourable directional characteristics (Tremsin et al, 2005). However, their limitation to thermal neutrons, considerable costs and the remaining problem of non-geometric transport make them unfeasible for CRNS.…”

Section: Implications For Practical Application Of a Directional Sensormentioning

confidence: 99%

Assessing the feasibility of a directional cosmic-ray neutron sensing sensor for estimating soil moisture

Francke

Heistermann

Köhli

et al. 2022

Geosci. Instrum. Method. Data Syst.

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Abstract. Cosmic-ray neutron sensing (CRNS) is a non-invasive tool for measuring hydrogen pools such as soil moisture, snow or vegetation. The intrinsic integration over a radial hectare-scale footprint is a clear advantage for averaging out small-scale heterogeneity, but on the other hand the data may become hard to interpret in complex terrain with patchy land use. This study presents a directional shielding approach to prevent neutrons from certain angles from being counted while counting neutrons entering the detector from other angles and explores its potential to gain a sharper horizontal view on the surrounding soil moisture distribution. Using the Monte Carlo code URANOS (Ultra Rapid Neutron-Only Simulation), we modelled the effect of additional polyethylene shields on the horizontal field of view and assessed its impact on the epithermal count rate, propagated uncertainties and aggregation time. The results demonstrate that directional CRNS measurements are strongly dominated by isotropic neutron transport, which dilutes the signal of the targeted direction especially from the far field. For typical count rates of customary CRNS stations, directional shielding of half-spaces could not lead to acceptable precision at a daily time resolution. However, the mere statistical distinction of two rates should be feasible.

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Neutron Collimation with Microchannel Plates: Calibration of Existing Technology and near Future Possibilities

Cited by 2 publications

References 12 publications

High resolution neutron radiography with very compact and efficient neutron collimators

High resolution neutron radiography with very compact and efficient neutron collimators

Assessing the feasibility of a directional cosmic-ray neutron sensing sensor for estimating soil moisture

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