Time dependence of the source recoilless fraction for a cobalt-57 in rhodium source

Wagoner, R. A.; Bullard, B. R.; May, Mark; Dickson, Scott N.; Mullen, J. G.

doi:10.1007/bf02398398

Cited by 11 publications

(4 citation statements)

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“…(16) allows for non-Lorentzian primary radiation densities as well [24,25]. Actually single line spectra remain Lorentzian, albeit the line broadens with the increasing parameter β.…”

Section: Evaluation Of the Cem Spectra Originating In The Highly Enrimentioning

confidence: 99%

Secondary Radiation Field Effects for the CEM Spectra

2010

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The secondary resonant radiation field and resonant absorption thickness effects on the Conversion Electron Mössbauer Spectroscopy spectra are analyzed for highly enriched resonant targets. It is shown that secondary field effect is important for the thick α-Fe foil enriched in the resonant isotope. Even for the polycrystalline sample traces of the coherent resonant field have been detected as the distortion of lines. Secondary field is discussed in detail. Suitable approximations to treat spectra originating from targets with significant resonant thickness developing secondary field composed of the incoherent and coherent parts are introduced. Finally, the formalism is applied to the high quality spectrum recorded for the enriched iron foil and correlation between contribution due to the secondary field and experimental line shape is investigated.

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“…(16) allows for non-Lorentzian primary radiation densities as well [24,25]. Actually single line spectra remain Lorentzian, albeit the line broadens with the increasing parameter β.…”

Section: Evaluation Of the Cem Spectra Originating In The Highly Enrimentioning

confidence: 99%

Secondary Radiation Field Effects for the CEM Spectra

2010

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“…Innovative courses based on project studies has helped many students to find self-discovery and opportunity for creativity in learning, Article on a personalized course in thermodynamics generated wide interest and promoted discussion about alternative approaches to teaching scientific material to students, Recent Research (Pub, , [41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57] Current research of J,G,M, centers on precision determination of the lineshape parameters in M6ssbauer effect (ME) spectroscopy, and the application of superintense ME sources to problems of elastic, quasl-elastic and inelastic scattering of the monochromatic recoilless photons from crystalline solids, The recent research investigations of J, Mullen can be broken into three major categories: lineshape measurements with M6ssbauer transmission and microfoil conversion electron (MICE) spectroscopy; scattering experiments using superintense ME sources to study charge density waves and anharmonic effects in crystals, and the study of the discontinuities in the internal fields for very precisely characterized magnetite,…”

Section: Innovation In Teaching: (Pub_6_7_33)mentioning

confidence: 99%

(Gamma scattering in condensed matter with high intensity Moessbauer radiation)

1989

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The QUEGS facility atMURR and thecryogenic scattering facility atPurdue University haveproduceda number ofnew results and demonstrated therangeofpotential applications ofhighresolution, highintensity M6ssbauerscattering. This work has beencarried out by both MU and Purdue researchers and includes published results on Na, W, pentadecane, polydimethylsiloxane and othersystems, with publications inpreparation on alkali halides, glycerol, and NiAl.Recently new collaborations have beeninitiated whichwill substantially ! i I t IJL _' Contents I. Introduction 3 II. Progress Report A. General Review of Progress During Last 4 Year Support Period. . .

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“…However, over the lifetime of a 57 Co source, the observed source recoilless fraction can change by more than 30%, changing the line shape and distorting the measurements of elastic scattering fraction. 15 By collecting full Mössbauer spectra, fitting them to the true line shape, and using sources only for a short period of time, we have eliminated these common sources of systematic error from our experiments.…”

Section: Introductionmentioning

confidence: 99%

Debye-Waller factors of alkali halides

1998

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Using very-high-intensity (ϳ70 Ci͒ 183 Ta Mössbauer sources, we have measured the Debye-Waller factors ͑DWF's͒ of sodium chloride, potassium chloride, and potassium bromide single crystals for several of the (h00) and (nnn) Bragg reflections. We have used an approach which properly accounts for thermal expansion over the temperature range of our experiment, from 90 K to 900 K, about 100 K below the melting point of our crystals. We have found that a procedure used to analyze data by earlier workers leads to incorrect parameters in the Debye-Waller factor exponent, and our procedure does not require empirical parameters to account for the effects of thermal expansion. Additionally, we find three items of significance. Contrary to earlier results, we observe that the cations and the anions have identical DWF's in NaCl and also in KBr. We observe terms in the expansion of the DWF exponential which are quartic in the scattering wave vector Q ជ in NaCl and KCl, with some evidence for a Q 4 term in KBr. The size of the Q 4 contribution is reported and varies with the direction of momentum transfer. We also observe that the Debye temperature and the coefficient of the anharmonic Q 2 term also vary with the direction of momentum transfer. We believe our data are the definitive evidence for a nonspherical thermal cloud in a cubic crystal; the ions have a larger amplitude of oscillation in the ͓h00͔ direction than in the ͓nnn͔ direction, contrary to the commonly held view of crystallographers that the most general form of the mean-square thermal motion is of an ellipsoid shape.

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Time dependence of the source recoilless fraction for a cobalt-57 in rhodium source

Cited by 11 publications

References 1 publication

Secondary Radiation Field Effects for the CEM Spectra

Secondary Radiation Field Effects for the CEM Spectra

(Gamma scattering in condensed matter with high intensity Moessbauer radiation)

Debye-Waller factors of alkali halides

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