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Handbook of Prompt GammaActivation Analysiswith Neutron Beams

Edited by

Gábor L. MolnárChemical Research Centre,Budapest, Hungary

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KLUWER ACADEMIC PUBLISHERSDORDRECHT / BOSTON / LONDON

Table of Contents

Preface (Zs.

Chapter 1. Principles of the PGAA method(Zs. Révay, T. Belgya)

l . Introduct ion

2.I Character ist ics of neutrons.. . . . . . . . . . . . . . . . . . . . . . . . . . .22.2 Fundamental processes occurr ing in PGAA .. . . . . . . . . . . . . . . .5

2.2.I Radiat ive neutron capture, or (n,y)-react ion.. . . . . . . . . . . . . . . . . . . . . . . . .52.2.2 Radiat ive neutron capture of epithennal neutrons.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52 .2 .3 Ac t iva t io r l . . . . . . . . . . . . . . . . . . . . . . . . . . . . .62 .2 .4 Isomer i c t rans i t ion ( IT) . . . . . . . . . . . . . . . . . . . . . . . . .62.2.5 Neutron capture with charged part ic le emiss ion . . . . . . . . . . . . . . . . . . .62.2.6 Neutron induced fission, or (n,f)-reaction...... .......62 .2 .1 E las t i c sca t te r ing . . . . . . . . . . . . . . . . . . .62.2.8 Thermal izat ion . . . . . .72.2.9 Inelastic scattering of fast neutrons, or (n,n') reaction ..........72.2.Í0 Nuclear reactions of fast neutrons.. .......72.2.11 Secondary react ions . . . . . . . . . . . . . .8

2.3 Probabi l i t ies of nuclear react ions. . . . . . . . . . . . . . . . . .82.4 Energet ics of the capture process.. . . . . . . . . . . . . . .142.5 React ion rate equat ions.. . . . . . . . . . . . . .17

2.5.1 Thin sample approximat ion . . . . . . . . . . . . . . . .182.5 .2 "B lack" sample approx imat ion . . . . . . . . . . . . . . . . . . . . . . . . . . .192 .5 . 3 Rea l s amp l e s . . . . . . . . . . . . . . . . . . . . . . . 19

3.1 Analyt ical propert ies. . . . . . . . . . . . . . . . . . .203.2 Characterization of prompt gamma spectra ................233.3 Dynamic range and detect ion l imit . . . . . . . . . . . . .25

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Chapter 2. Beams and Facilities(R.M. Lindstrom, Zs. Révay)

Table of Contents

1. Basic parts of the PGAA

1 . 1 Neutron sources . . . . . . . . . . 3 1I.2 Shaping and tailoring the neutron beam .....34

I . 2 . 1 Co l l ima to r . . . . . . . . . . . . . . . . . . . . . . . . . . . 341.2.2 Neutron fi lters .....34

1.3 Neutron guides and focusi . ,g . . . . . . . . . . . . . . . . . . . . . .351.3.1 Straight guides . . . .361.3.2 Curved guides . . . . .311.3.3 Supermirror guides . . . . . . . . . . . . .381.3.4 Neutron lenses . . . .381.3.5 Dif fracted beams . . . . . . . . . . . . . . . . .40

1.4 Neutron absorbers and shieldins: materials issues ......401.5 Shut ter . . . . . . - . . . . . . . . . . . . . . . . .421 .6 Beam tube . . . . . . . . . . . . . . . . . . . 421.7 Sample ho lder . . . . . . . . . . . . .431.8 Beam s top . . . . . . . . . . . . . . . . . . .43

2. Neutron flux mapping and monitoring

2.I Average neutron wavelength and beam temperature............ ......432.2 Monitor ing and mapping . . . . . . . . . . . .45

3. Additional shieldins and backsround issues...... .............41

References

Chapter 3. Samples and Standards(R.M. Lindstrom, Ch. Yonezawa)

Sample cons idera t ions . . . . . . . . . . . . . . . . . . . .59

1 .1 Samp l e s i 2e . . . . . . . . . . . . . . . . . 591.2 Sample shape . . . . . . . . . . . . . .60

Í.2 .1 Neut ron se l f -absorpt io r r . . . . . . . . . . . . . . . . ' . . . . .611.2.2 Neutron scatter ing within the samp1e.. . . . . . . . . . . . . . . . .621.2.3 Gamma-ray sel f-absorpt ion . . . . . . . . . . . . . . . .65

Standards and b lanks . . . . . . . . . . . . . . . . . . . . . .66

2.1 Preparat ion of standards.. . . . . . . . . . . . .662.2 Reference materials ....672.3 Suitable blanks.. . . . . . . . . . .68

4.

References

Table of Contents

Chapter 4. Gamma-Ray Spectrometry(T. Belgya,Zs. Révay)

l. Introduction

2. Basic

2.1 Detectors . . . . .122.2 E lec t ron ios . . . . . . . . . . . . . . . . . .74

2.2 .1 Ana log e lec t ron ics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .142.2.2 Digital signal processing .....75

2.3 Dead t ime and p i le -up. . . . . . . . . . . . . . . . .762.4 Response function of germanium detectors......... .......78

3. Cal ibrat ion procedures.. . . . . . . . . . . . . . . . . . .80

3.1 Energy resolut ion . . . . . . . .803.2 Sys tern non l inear i ty . . . . . . . . . . . . . . . . . . . .813.3 Detector efficiency ......83

3.3.1 Wide energy range efficiency calibration ...........833.3.2 Intr ins ic and geometr ic eff ic iency.. . . . . . . . . . . . . . . . . . . . . .863.3.3 Geometry factor for col l imated detectors . . . . . . . . . . . . . . . . . . . . . . . . . . .873.3.4 Active and effective volume of the sample .........89

3.4 Calibration sources .....90

4. Opt imizat ion of detect ion . . . . . . . . . . . . . . .91

4.1 Spectralbackground

5. More sophist icated detect ion systems.. . . . . . . . . . . . . . . . . . . . . . . . . . . .96

5.1 Compton suppressed and pair spectrometers ..............965.2 Composite germanium detectors........... ......995.3 Coincidence techniques . . . . . . . . . . . . . .995.4 Chopped-beam PGAA . . . . . . . . . . . . . .101

Chapter 5. Quantitative Analysis(Ch. Yonezawa)

1. Introduction

2. Elemental

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v1l1 Table of Contents

3.2 Relat ive standardizat ion.. . . . . . . . . . .1163.3 Intemal standardizat ion.. . . . . . . . . . . .118

4. Sources of error. . . . . . . . . . . . . I27

4.1 Spectral interference.. . . . . . . . . . . . . . . . I274.2 Gamma-ray background ...........129

5. Util ization of short-l ived decay gamma rays ......... ....... 133

Chapter ó. Applications of PGAA with Neutron Beams(D.L. Anderson, Zs. Kasztovszky)

1 . In t roduct ion . . . . . . . . . . . . . . . . . .137

2. Appl icat ions in Chemistry . . . . . . . . . . . .138

2.1 Analys is of Cert i f ied Reference Mater ia ls. . . . . . . . . . . . . . . .1382.2 Isotopic and Chemical Composit ion Studies . . . . . . . . . . . .1392.3 Chemical Matr ix Studies . . . . . . . . . .140

3. Industry-Related Applications and Materials Science ..................141

3.1 Related Reference Materials .....1413.2 Ores, Metal Alloys, and Construction Materials. ......I423.3 Foss i l Fue l s . . . . . . . . . . . . . . .1433.4 Catalysts. . . .1443.5 Glass and Semiconductors ........t453.6 Nuclear Tecturology Appl icat ions . . . . . . . . . . . .1453.1 Mater ia l Composit ion and Processing.. . . . . . . . . . . . . . . . . . . . .146

4. Geology, Geochemistry, and Cosmochemistry .............148

4.1 Geochemical Reference Mater ia l Analys is. . . . . . . . . . . . . . .1484.2 Geology . . . .1494.3 Cosmochemistry . . . . . . .151

5. Ar t and Archaeo logy . . . . . . . . . . . . . . . . . . . . .152

5.1 S tone too l s . . . . . . . . . . . . . . . . I525.2 Ceramics . . .1535.3 Pigments and paint ings.. . . . . . . . . . . .1545.4 Meta l ob jec ts . . . . . . . . . . . . .154

6. Food and Agriculture ....156

6.1 Certif ication of Reference Materials. ........ 1566.2 Analys is of Food.. . . . . .157

7. Environmental Studies. . . . . . . . . . . . . . . . . .158

Table of Contents

I I Atmospher ic Gases and Part ic les. . . . . . . . . . . . . . 1587.2 Water and Sediment Pol lut ion.. . . . . . . . . . . . . . . . .159

8 . B i o l ogy . . . . . . . . . 160

8.1 Biological Matrix Reference Materials .....1608.2 Human and Animal Studies . . . . . .161

9. Medic ine . . . . . . .162

9.1 Boron Neutron Capture Therapy ..............1629.2 Other Med ica l S tud ies . . . . . . . . . . . . . .163

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164

Chapter 7. Prompt Gamma-Ray Spectrum Catalog(Zs. Révay, R.B.Firestone, T. Belgya, G.L. Molnár)

1 . In t roduct ion . . . . . . . . . . . . . . . . . .113

2. Evaluation of prompt gamma-ray data .........174

2.1 Sources of the evaluat ion . . . . . . . . . .1142.2 Measurements in Budapest . . . . . . .\142.3 Eva luat ion . . . . . . . . . . . . . . . . .175

3. Spectra and tables for e lements . . . . . . . . . . . . . . . . . . . .116

3.1 Format of the elemental spectra. . . . . . . . . . . . . . . .1763.2 Format of the elemental tables ..1793.3 Background spectra .. 186

Re fe r ences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186

3.4 Spectra and tables for each element.. . . . . . . . .186

Appendices Reference Data

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(R.B. Firestone, G.L. Molnár, Zs. Révay)

Fundamental constants. . . . . . . . . . . . . . . . . .365

Propert ies of chemical e lements.. . . . . . . . . . . . . . . . . .367

Isotopic data.. . . . . . . . . . . . . . . . .31I

Rad ioac t ive nuc1 ides . . . . . . . . . . . . . . . . . . . . .380

X-ray energies and intensit ies. . . . . . . . . . . . . . . . . . . . . . .390

Energy and intensity standards . . . . . . . . . . . . . . . . . . . . .393

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Table of Contents

Thermal neutron capture data.. . . . . . . . . . . . . . . . . . . . . .400

Resonance parameters and Westcott g factors ..............410

Neutron capture cross section of elements............. .......4I2

Preface

Prompt Gamma Neutron Activation Analysis (or the more common usage, PrornptGamma Activation Analysis, abbreviated as PGAA) is based on one of the most basicnuclear reactions, the radiative capture of neutrons. This nuclear reaction takes place foreach isotope of every element, with the single exception of aHe. Therefore, in principle,a complete elemental and isotopic analysis can be performed using PGAA. Neverthelessthis versatile nuclear technique has mainly been used as a supplementary analytical tooluntil recently. Many recent developments have been achieved at the leading laboratoriesof this field that make it timely to summarize the results in the form of this handbook.

The creation of this book was possible thanks to the cooperation of many specialists:radiochemists and physicists working in the fields of PGAA, traditional neutron activa-tion analysis (NAA), gamma spectroscopy and nuclear data evaluation. The PGAA fa-cility at the collimated thermal beam at NISI USA began operation in the early eightiesand has been mainly used for the analysis of biological samples by D. L. Anderson. Asecond PGAA system was installed at a guided cold neutron beam at the same reactorby R.M. Lindstrom towards the end of the 1980's. APGAAfacil ity operating with ei-ther the thermal or the cold beam was started at JAERI in Japan under the leadership ofChushiro Yonezawa in the early nineties.

The thermal neutron guides started operating at the Budapest Research Reactor in1994. A PGAA facility of the Budapest Neutron Center was established in 1996. Sincethat time thousands of PGAA measurements were performed there for different fields ofapplication and to the development the PGAA technique. A cold neutron source wasinstalled at the reactor in 2000 at Budapest, improving the capabilities further.

The Department of Nuclear Research of the Institute of Isotopes, led by Gábor L.Molnár, proved to be an ideal laboratory for adopting and developing fuither the PGAAmethod. Professor Molnár organized the cooperation of colleagues from many differentbackgrounds to accomplish a very significant improvement in the methods and tech-niques of PGAA. Tamás Belgya developed y-y-coincidence techniques for PGAA appli-cations and has been responsible for the sophisticated electronics. Zsolt Kasztovszkyhas been in charge of arranging different applications, and I myself have established thePGAA analytical data library and developed data reduction programs and techniques.

The large number of gamma-ray peaks appearing in prompt gamma spectra requiresan accurate calibration of the detection system, and a reliable and reproducible identifi-cation of gamma lines. The principal reason that this useful technique did not become astandard nuclear analytical method has been the lack of an accurate and complete ana-lytical library. The poor reliability of available spectroscopic data discouraged manyscientists from using the PGAA (Molnár 2000). In parallel with the new, precise library

x l l Preface

measurements performed in Budapest, a thorough database was constructed as part of aCoordinated Research Program of the International Atomic Energy Agency. The libraryprovided in this book results from the IAEA evaluation led by Richard B. Firestonefrom Lawrence Berkeley National Laboratory (IAEA 2004). It combines the preciseBudapest elemental measurements with detailed isotopic measurements from the scien-tific literature.

Many review ar1icles were published about PGAA and its applications (Anderson é/al. 1982, Greenwood 1919, Lindstrom et al. 1997, Lindstrom et al. 1994, Paul andLindstrom 2000, Shaw 1999) and a dedicated book has also appeared (Alfassi andChung 1995). The idea of publishing a handbook that contains all up-to-date informa-tion needed to perform reliable analysis with the PGAA method, was born in the Buda-pest group. This new handbook summarizes the experiences collected at those PGAAfacilities equipped with Compton-suppressed HPGe detectors and using cold and ther-mal neutron beams. This is the first time that an atlas of prompt gamma spectra with adata library for every naturally occurring element as measured with a high-resolutiongermanium detector has been published. It is mainly intended for analytical applica-tions; however the tables have been constructed in a way that they could be used inother fields, as well.

In Chapter 1 the fundamentals of the PGAA method are given. Chapter 2 discussesbeam and facility construction material considerations, and the most important facilitiesare also described. Chapter 3 addresses sample preparation and the use of standards.Chapter 4 is dedicated to the spectroscopy, the setting up of the data acquisition elec-tronics and the calibration procedures required for the accurate analysis. Chapter 5 out-lines the process of PGAA quantitative elemental analysis and discusses the most im-portant factors affecting the analytical results, and Chapter 6 gives examples of themany applications of PGAA performed with neutron beams. Chapter 7 contains the ex-perirnental prompt gamma ray spectrum library measured in the Budapest thermal andcold neutron beams, and lists up to 100 of the most prominent prompt and delayedgamma rays. Tl-re appendix provides useful tables of frequently used nuclear and ele-mental data. The CD supplement contains high resolution drawings of the spectra (inPDF format) and the complete library of prompt and delayed gamma rays.

Gábor Molrrár began tlre preparatiorr of this handbook in the year 2000. He designedthe content of the book, invited the co-authors to participate and coordinated the project.He planned to finish the book in 2003, but last fall his enthusiasm seemed to have dete-riorated. He started reviewing the manuscripts, made some changes in chapter 3, gener-ated the headings in Chapter '7 and thoroughly verified the data library and the atlas.Unfortunately he could not finish this work and was unable to start writing the chaptershe was responsible for. Tragically, he passed away shortly after the Christmas holidays,which were spent in hospital. The rest of the work on the Handbook was passed on tohis colleagues in the Department of Nuclear Research. Tamás Belgya and myself haveprepared the missing chapters, Zsolt Kasztovszky has undertaken the updating of thechapter on applications of the method, while I finished the editing of the book.

Gábor Molnár's contributions to the development of the PGAA method were bothbroad-based and essential. In addition to this book, a special journal issue dedicated tohis memory is also being edited, includes many papers on the projects he took part in or

Preface xl l l

inspired in different laboratories. These papers, are cited throughout this book, and areto be published in the Gábor Molnár memorial issue of the Journal of Radioanalyticaland Nuclear Chemistry, which is will appear at the end of 2004.

The authors hope that this handbook will contribute to the propagation of PGAA asa powerful nuclear analytical technique.

Let me give special thanks for the valuable and friendly support of Richard Lind-Strom, Richard Firestone and also my colleague Tamás Belgya' who helped me consid-erably in solving numerous problems that arose while completing this book. The carefulproofreading and the useful advice of Jesse L. Weil are also gratefully acknowledged.

Zsolt Révay

Budapest, June 28, 2004.

References

Alr.esst, Z. B., CHtxG' C.' l995' Prompt Gamma Netúron Activation Analysis, (Boca Raton: CRC Press).

ANDERSoN, D.L.,Zot-rEn, W. H., GoRDoN, G. E., WALTEnS, W. B., LrNosrRoM, R. M., 1982, Ileutron-Capture Gamma-Ray Spectroscopy and Related Topics (lnst. Phys. Ser. 62), edited by Maier, B. (London:Inst. Physics), Chapter: Neutron-Capture Prompt Gamma-Ray Spectroscopy as a Quantitative AnalyticalMethod, p. 655.

GnPENwooo, R. C., 1979, Proceedings ol the Third Internationctl Sympositrm on IYeutron-C-apttu'e Gamma-Ray Spectroscopy and Related Tbpics, edited by Kane, W. R. (New York: Plenum), Chapter: Practical Ap-plications of Neutron Capture Gamma Rays, p. 441.

LtNostRona, R' M., PAUL, R' L., Walrpns' w. B.' MolNÁn, G., |994' Capture Gamma-Ray Spectroscopy anc|Related Tbpics, edited by Kern, J. (Singapore: World Scientifrc), Chapter:Analytical Applications of ColdNeutron Capture and opportunities Íbr Nuclear Physics, p. 955.

LtNosrRov, R. M., ANDERSoN, D. L., PAUL, R. L., 1997, Proc. 9th Internat. S1,mp. Capture Gamma-RaySpectroscopy and Related Topics, edited by G.L' Molnár' T. Belgya, Zs. Révay (Budapest: Springer), Chap-ter: Analy.tical Applications of Neutron Capture Gamma Rays, p. 693.

MolNÁn, G. L.' 2000' J. Radioanal. Nucl. Chem.,244.27.

Paul, R. L., LtNDStRoM, R. M., 2000, J. Radioanal. Nucl. Chem., 243, l8l.

SHaw" D. M.. 1999.J. Neutron Res. .7. 181.