Folder 57: The Crocker Historical and Archaeological Project, 1991
This file contains a typewritten version of the Crocker Historical and Archaeological Project, taken from the Crocker Nuclear Laboratory Annual Report 1990-1991. July 1991.
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1991
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This file contains a typewritten version of the Crocker Historical and Archaeological Project, taken from the Crocker Nuclear Laboratory Annual Report 1990-1991. July 1991. |
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Saint Louis University Libraries Digitization Center |
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1991 |
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sluoai_speccoll-1479 Folder 57: The Crocker Historical and Archaeological Project, 1991 Crocker Nuclear Laboratory Proton-induced X-ray emission; Imaging systems in archaeology; Archaeometry; Antiquities -- Analysis This file contains a typewritten version of the Crocker Historical and Archaeological Project, taken from the Crocker Nuclear Laboratory Annual Report 1990-1991. July 1991. 1991-07 2011 image/pdf 67 1 57_Item 0001.pdf Thomas A. Cahill Papers--Crocker Historical and Archaeological Project, 1981-2009 The items in this folder are part of the Thomas A. Cahill Papers--Crocker Historical and Archaeological Project, 1981-2009. They are from Series 1: Thomas A. Cahill Research Papers, 1981-1994. This series consists of various research papers and published articles based upon Dr. Cahill's research using Particle Induced X-ray Emission (PIXE) techniques in analyzing inks and papers. 67 1 57 Permission to copy or publish must be obtained from the Saint Louis University, Pius XII Memorial Library, Special Collections Department Saint Louis University Libraries Digitization Center text/image eng Saint Louis University Libraries Special Collections, Archives & Manuscripts Taken from Crocker Nuclear Laboratory Annual Report for 1990-91: Group L••••• r: Bruce Kusko, Crocker Nuclear Laboratory BHrd If Oirectors: Thomas Cahill, Department of Physics Richard Sch'w'ab, Department of History Robert Eldred, Crocker Nuclear Laboratory Daniel Wick, Integrated Studies and Director, Summer Sessions Seymour Ho'w'ard,Department of Art and Art History Charles Higgins, Professor Emeritus, Department of Geology Donald Kunitz, Special Collections, Shields Library ActiYe Partlel pints # U.C. DlYis James Shackelford, Department of Materials Engineeri ng, and Associate Deen, Undergraduate Engineeri ng Thomas Gill, Earth Science and Resources Michael Taylor, Department of Civil Engineeri ng Deborah E111ott-FiSk, Department of Geography Deborah Sha'w'-Warner, Department of (Avian Sciences) Stanley Margolis, Department of Geology Dennis Dutschke J Department of French and Italian Douglas McColm, Department of Physics Michael Chandler, Fire Department Javier Hi randa, Crocker Nuclear Laboratory (on leave from the National Autonomous University of Mexico) Paulo Cruvi nel, Crocker Nuclear Laboratory (on leave from the Brazilian Institute for Agricultural Research) Roberto Morales, Crocker Nuclear Laboratory (on leave from the University of Chile, Santiago) Xianzhou Zeng, Crocker Nuclear Laboratory (on leave from Fuden University, Shanghai) Affiliated InYlstilltlrs Consuelo Dutschke, Davis and Hunti ngton Library Joyce Wilson, San Francisco Anthony Bliss, Curator of Manuscri pts, Bancroft Library, U.C.Berkeley Robert Anderson, Dept. of Materials Science, San Jose State University Peter Englert, Dept. of Chemistry, San Jose State University Ed'w'ardvon der Porten, Director, Treasure Island Huseum Robert Pwer, NovaAlbion Foundation David Wood'w'8rd,Professor of Geography, University of Wisconsi n T1mothy Barrett, Director, Papermaki ng Facility, 10'w'8Center for the Book, University of 10'w'a,Iwa City Peter Zahn, Institute of Library Sciences, Free University of Berlin Hans Mammsen, Research Physicist, University of Bonn Michel Menu, Chief Scientist, Accelerator Laboratory, Louvre Museum Elizabeth DelangeI Curator I Department of Egyptology, Louvre Huseum CHAPs 90-91 Annua.l Report page 2 Students Roger King Scott Vosburg Peruo •• l: 0.5 FTE Fundin,: CNLand Unlversity grants I. INTRODUCTION The Crocker Historical and Archaeological Program, or CHAP,consists of an informal group of scholars in the natural sclences and humanlties 'w'hoare engaged in historlca1, art-historical J bibl10grap hical , and archaeological research usi ng the CNLcyclotron. CHAPevolved out of a collaboration bet'w'eenTom Cahill's physics research in the Air Quality Group and Dick 5ch'w'ab's historical research on Diderot's Encyclopedia. 5i nee 1978 the CHAPgroup has been involved in the development of high-energy ion- beam anal ysis techniques, PIXEand PIGMEJ appl1ed to fragile 'w'orks of art and archaeology. We have concentrated our efforts on books and manuscri pts J and can no'w'maleecompletel y non-destructive elemental anal yses of the inks, papers, parchments J and pigments of the most rare and fragile books, manuscri pts, and historical documents J 'w'ith unprecedented sensitivity and precision. We are maki ng great strides in the study of the history of pri nti ng, by uncoveri ng ne'w'1nformation that sheds 110hton the fi rst pri nti ng shop that produced the magnificent "Gutenberg" B1ble. The success of the program in the past has been due to the active and sustai ned cooperation bet'w'eenscholars in 'w'1dely differi ng fields. 5i nce our techniques can be usd to anal yze al most any of the materials used in 'w'orks of art or archaeology (ceramic J metal J stone J glass J textile I and others) , ve have to be careful to li mit our efforts to 'w'en-chosen projects. for this reason 'w'e have formed an informal "Board of Directors" 'w'hohave the role of choosing and coordinating these multi-disci pl1nary projects. We 'w'111undertake a projects onl y if 'w'ehave the cooperation of a UC Davis scholar 'w'hois 'w'ellinformed about the questions and problems of 'w'hoever proposes a project. At the same ti me the technical capab11ities must be made clear to the proposer, so they understand just 'w'hatcan and can not be done 'w'ithion- beams. This is necessary to hel p i nterperate the results of an analysis and understand 'w'hatit means in an historical or archaeological context. The CHAPprogram 'w'8S on hold bet'w'eenJuly 1988 and August 1990 as Bruce Kusko, technical coordi nator , 'w'entto Paris to help set up a facility for the ion- beam anal ysis of 'w'orks of art and archaeology at the Louvre Museum. While overseas, Bruce made many contacts and is continuing his collaboration 'w'ith museum scientists and curators at the Louvre. Heis also involved ina German program to develop ion- beam and synchrotron radiation techniques for the anal ysis of German incunabula. Bruce returned to CNLas the head of the CHAPgroup and is no'w' 'w'orking to diversify thei r anal ytical capabilities. CHAPis also reponsible for all samples not in the "standard" aerosol f11ter form. Non-standard samples anal yzed duri ng the year i ncl udedarson debris (burned concrete I melted metal) I tree snails, and industrial plate glass. (see part III) CHAPs 90-91 Annual Report page 3 II. EXPERItlENTAL/TECHNICAL Most of the 'Workdone in the past year led to improvements in our anal ytical capabilities. A. Nev SNOUT The present beam-i n-et r system that 'Wecall the proton milli probe is designed for books and manuscri pts, and 'Works 'Wellfor other objects that are flat. It is difficult to anal yze objects that do not have a flat surface or are unusuall y large. for this reason a ne'Wextension to the beam-i n-et r system has been designed and built, affectionatel y kno'Wnas the "snout". (See figure 1.) The snout is made of brass and is 11ned vttn polyethylene. The f1nal carbon c0111mator ~ used to define the beam size on target, is fixed, but interchangeable 'Withother sizes on hand. (0.5, 1.0. 2.0. and 3.0 mm). The snout has a tel escoping feature that allo'Ws us to change the beam energy ina quiCk and si mple manner. (By leavi ng the target and detector fixed, the snout is moved upstream and the distance the protons travel in air tncreeses, so their energy (on target) decreeses.) This feature is very useful for depth- profili ng studies. A Faraday cup can be positioned at the target spot to measure the beam current. and s'Wung a'Wayfor sample anal ys1s. nurt ng sample anal ys1s a jet of a1r ts d1rected to the p01nt of proton impact. This ai r cools the sample duri ng irradiation and together 'Withthe beam- pulsi ng system ensures that no damage occurs to fragl1e objects. Adetector stand 'Wasbunt to keep the detector at 135 degrees to the proton beam. Target to detector distance is easil y adj ustable. At this back angle 'Welose solid angle but gai n sensitivity sionce the background 1s 10'Wer. Atarget holder is being designed~ incorporating remotely controlled X-V positioning devices, to be used for both large and small samples. Presentl y 'vieare usi ng a target holders fashioned from our book lectern and computer plotter. Target placement is aided 'Witha crossed laser beam alignment system. Runni ng 'Withthe proton beam in ai r 'Whileexperi menters and others are present requi res special caution and rigorous safety procedures must be follo'Wed.Ane'Wsystem of safety interlocks had to be designed for the snout system on beam 11ne 1B. This i nclOO8sinfrared photocells that triggers a beam stop if anyone~ or anyone's hand~gets too close to the proton beam. B. PIGtlE We have added the ab111tyto anal yze Objects by detect1ng the characterist1c gamma- rays emitted during proton bombardment. This technique~ Proton Induced Gamma-Ray Emission~ or PIGME~is sensitive to elements difficult or i mpossi ble to detect 'With PIXE~such as Na~f ~Li~Be~ B~N, Mgand 11.1. In a sense, PIGMEis very si milar to PIXE, usi ng nearl y identical detectors I electronics ~and data acquisition and reduction codes~and the t'Wocan be performed s1multaneousl y. PIGMEcross-sections are much 10'Werthan PIXEcrees-secttena, so higher beam currents are needed, 'Whichare po!si bly damaging to sensitive objects. Minimum detectable 11mits vary vt del y 'Withelement, beam energy. and even laboratory~ si nce practical detection 11mits are set by the high energy gamma-ray backgrOUndin the laboratory. Several tests have been performed 'With NISTstandards and plate-glass samples usi ng a gamma-detector on loan from La'WrenceLivermore Laboratory. The preliminary results have been encouragl ng but more 'Work 8t111need8to be done before PIGME can be performed rout1 nel y, CHAPs 90-91 Annual Report page 4 c. Proton -Hicro--probe The smallest beam size available 'w'ithour standard "beam-in-air system, the proton mm1 probe, 1s on the order of 0.3 m1111meters (300 m1crons). It ts somet1mes useful to have a beam size on the order of 30 microns. Maps of the elemental concentrations on the surfaces of samples, or the profl1e of elemental concentrations across an interface can be obtai ned, for esample, in geological or biological samples. Over the last year the microprobe project has been revived. Due to 11mited resources ve decided to achieve a small beam by c0111mattcn, tradi no high beam currents and micron resol ution for si mpllcity of design. Our most successful approach is based on the colli mation of the proton beam 'w'1than orthodontic "needle" 1 cm long 'w'ithan inner diameter of 150 microns. Duri ng one run a beam size of 300 microns (fWHM) 'w'asmeasured by scanni ng a 25 micron plati num 'w'ire as a target. Beam currents vere 20 - 30 p1coamperes. Th1s ts no better than 'w'hatis possi ble on the old system, and it may be that the edge effects are larger than 'w'eexpected. There is also a chance that protons are getti ng around the needle. The needle presents problems of alignment, so 'w'evill try apertures commerciall y available for laser systems. We are confident that a beam size belo'w'50 microns vttn an adequate beam current is poss1ble. We built a target chamber to hold small samples in a vacuum, and a beam-in-air microprobe is being designed. The ulti mate beam etze, around 100 microns, is 11mtted by scatteri ng in the exit 'w'indo'w'and the ai r. D. Thick target a.l pta (GUEPIX#PIXAN) Our spectrum anal ysis code RACE,'w'hich'w'orks so vell on thi n aerosol filter samples, is not suitable for thick targets encountered in art and archaeological 'w'ork. We have recentl y obtai ned t'w'ocodes designed to quantitati vel y anal yze thick target spectra, a task much harder than anal yzi ng thi n target spectra. They 'w'111be installed in the summer of 1991 and eval uated vtth a number of thick target standards. {One program, GUEPIX,is a versatile soft'w'8re package for fitting PIXEspectra, extracting peak 1ntenstttes, and convert1 ng to elemental concentrations. It includes the latest atom1c physics data bases, the most sophisticated peak descri ption of all the competi ng programs, a special non- 11near least-squares fitti ng to prevent premature ell mination of 'w'eakpeaks, an easy and accurate background subtraction (self-adjusting; user can't mess it up.), and exact treatment of matrix absorption and secondary enhancement effects. The other program, PIXAN,is also a good program but includes many more approximations in arrtvt ng at the elemental coneentrettens. {In addit10n, my exper1ence 'w'ith PIXAN1n Par1s sho'w'edme PIXAN'sbackground subtraction method(s) led to inaccurate results. } III. ANALYSIS RUNS (see full report for details) A. Hi,h-temperature acceleralt fire Simples B. Pittsburg Plate Glass (metll oxide coatings) D. Florida Tree Snails CHAPs 90-91 Annual Report page 5 IY. fUTURE PLANS A. Plate of Brass The "Plate of Brass", said to be a relic of the visit of 5i r Francis Drake to northern California (Nova Albion) in 1579 is scheduled to be analyzed in July. Our plan is to anal yze the plate in many () 100) places, across the front, back, and sides to determ1 ne the cons1stency of the Cu/Zn rattc. The essumpttcn te that a Cu/Zn rene wUhl n 0.5~ across the plate means the plate is modern rolled brass, available onl yin recent ti mesI whereas a varlation in the Cu/Zn rat10 by 10 - 20~ 1ndlcates that the plate has probabl y made by the calami ne process J then cast or hammered into shape, techniques known in the 16th century. Ofcourse we will compare the results of the Plate with other brass objects, some modern, and some lenownto be from the 16th century. We prom1sed the Bancroft nothl ng except more information about the Plate. We would be the fi rst to admit that we can never prove beyond doubt that the Plate was left by Drake. In additlon to study1ng the un1formity of the ccmpestttcn of the Plate we w111analayze the composition of the pati ne, and compare the pati na on the front with the pati na on the back. (Perhaps an old brass plate was used so the pati na on the back may be genul ne while that on the front is artificial.) We will also look for evidence of the tool used to make the i nscri ption which was traced or i mpreesed, not cut or engraved, and evidence of the silver sh1111ng left 1n the COln hole and i ron stakes in the square holes. B. EI1•••• r. Chauc.r The Board of Trustees of the Huntington Library has approved the preparation of a (state-of- the-art) facslmile of the prize manuscript in their collection--the Ellesmere Chaucer. The Ellesmere Chaucer is generall y regarded as the fi nest medieval vernacular manuscri pt in English, written someti me around 141 O.Alongwith the facsi mile, a companion volume of scholarl y essays will be made which will explore a wide variety of topics related to this landmark manuscri pt. The preparation for the facsi mile edition will i nclude the disbi ndino, repai r, and flattenl ng of the parchment leaves. In thls condttlon the leaves are idean y suited for anal ysls with the proton milli probe. Daniel Woodward, overall manager of the project, has accepted our proposal to have the unbound leaves brought to Davis for a cyclotron exami natlon of the 1nks, pigments, and parchments. We feel that our exami nation of the manuscri pt could be useful in disti nguishi no gradat10ns in 1nks used, a beg1nn1no toward ascerta1 n1ng the number of artists who worked on the portraits and clarifyi no the disputed use of a styl us in three pictures of the horses. Astudy of the parchments used may shed light about the preperetten of the manuscr1 pt. It 1s antici pated that other scholars will have suggestions about further 11nes of investigation. The prospect for anal yzing the Ellesmere Chaucer 1s i mmensel y exctt1ng, not only because of the dlscover1es that may be made concerning this significant manuscript, but also for the criteria that the project will set for the sctenttnc support of manuscript study. The project w111beg1n when enough money has been raised by the Huntington to complete the project. Since they hope to publish the facsi mile and the companion volume in 1994, to coinclde with the 75th anniversary of the Huntington Library, the cyclotron anal ys1s1s scheduled to be completed by the end of 1992. C. Marbl,".pl" CHAPs90-91 Annual Report page 6 The addition of PIGME,the snout, and selective filtering techniques to our arsenal means additional elements can be detected to better characterize marble samples. The goa11s to d1st1ngu1sh quarr1es by the1r m1nor and trace element ccmpeettten. The problem is the inhomogeneous nature of the trace elements (rare earths, ... ) usuall y measured by NAA.It has been difficult to get a chemical "fi ngerpri nt" of a quarry with wh1ch one can attri bute a particular artifact. We have el ready shown (ref?) that by looki ng at the minor elements, (sr , Mn, Fe, K, 5, ..Mg), and grai n morphology, some quarry's can be dist1ngu1shed from other quarry's. When these results are combined 'w'ithstable isotope data obtained else'w'here, more quarries are dtsti nguishable, but severe overlaps remai n. We are studying the marble from the Carrara district of Italy, and have detailed samples from one quarry and several samples from other quarries in the area. We feel that the on1y 'w'ayto disti nguish quarries is to combi ne the results of many techniques. D. Gutenber,leaf (carbon) Although we discovered the remarkable secret of Gutenberg's fi rst typographic ink, large amounts of copper and lead, 'w'ehave no idea ho'w'much of the rich blackness is due to carbon. But it is not easy, at least non-destructive1 y, to determi ne just how much carbon and other light elements, (0, N, ..J are there. 5i nce PIXEcannot be used direct1 y to obtai n the concentrations of light elements, an i ndirect method of determi ning these elements has been devised. Essentially, the paper ts used as a source of X-rays, (generated by the proton beam), 'w'hichthen pass through the ink on thei r 'w'ayto the detector. The ink absorbs some of these X-rays, espec1all y the l1ght ones (5, K, Car.). By compar1 ng the val ues vttn those of an anal ys1s without ink, 'w'ecan arrive at a measure of the mass absorption constant of the ink. We can then see how much the copper and lead, found by d1rect PIXE,account for this absorption, and concl ude that the difference is due to the light elements, which we assume is most1y carbon. 5ee full report for the followi ng: ..Y. MEDIA COYERAGE 90- 91 YI. COLLOQUIAl PUBLIC ADDRESSESI INfORMAL TALKS 90-91 YII. PUBLICATIONSI REPORTS# AND ABSTRACTS 90-91 http://cdm17321.contentdm.oclc.org/cdm/ref/collection/speccoll/id/1479 |