The INES project was sponsored by the CNR Neutron Spectroscopy Advisory Committee, stressing the importance of realizing an Italian Neutron Experimental Station (INES) at the world most powerful pulsed neutron source (ISIS,

Rutherford Appleton Laboratory, UK) and evidencing the strategic value that such a test station would assume in the field of applied sciences like, for example, chemistry,

material science, Earth science, crystallography, and last, but not least, in the field of science applied to the study of cultural-heritage artifacts

Grazzi, F.

Celli, M.

Siano, S.

Zoppi, Marco

English

Vedeld, Paul

Brage NMBU

Stakeholder Analysis, Natural Resource Management and Governance – Comparing approaches

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DOI 10.1393/ncc/i2006-10039-5IL NUOVO CIMENTO Vol. 30 C, N. 1 Gennaio-Febbraio 2007Preliminary results of the Italian neutron experimental stationINES at ISIS: Archaeometric applications(∗)F. Grazzi(1)(2), M. Celli(1), S. Siano(2) and M. Zoppi(1)(∗∗)(1) CNR, Istituto Sistemi Complessi: Sezione di FirenzeVia Madonna del Piano 10, 50019 Sesto Fiorentino, Italy(2) CNR, Istituto di Fisica Applicata “Nello Carrara”Via Madonna del Piano 10, 50019 Sesto Fiorentino, Italy(ricevuto il 31 Ottobre 2006; pubblicato online il 9 Febbraio 2007)Summary. — The INES project was sponsored by the CNR Neutron SpectroscopyAdvisory Committee, stressing the importance of realizing an Italian Neutron Ex-perimental Station (INES) at the world most powerful pulsed neutron source (ISIS,Rutherford Appleton Laboratory, UK) and evidencing the strategic value that sucha test station would assume in the field of applied sciences like, for example, chem-istry, material science, Earth science, crystallography, and last, but not least, in thefield of science applied to the study of cultural-heritage artifacts.PACS 07.90.+c – Other topics in instruments, apparatus, and components commonto several branches of physics and astronomy.PACS 61.12.-q – Neutron diffraction and scattering.PACS 81.90.+c – Other topics in materials science.1. – IntroductionNeutron Scattering is one of the most powerful diagnostic techniques available for sci-entific and technological research in material science. This technique, even though widelyemployed among the technologically most advanced countries, is not as much widespreadwithin the Italian scientific community, as the level of the GDP (Gross Domestic Product)and the political and social weight of the country would deserve. Among the various rea-sons responsible for the present situation, the most important is the absence of nationalneutron sources available to the scientific community. Indeed, the beginning of the 70’switnessed an absolute minimum, in Italy, of the neutron scattering activities. Followed(∗) Paper presented at the Workshop “RICH—Research Infrastructures for Cultural Heritage”,Trieste, December 12-13, 2005.(∗∗) E-mail: marco.zoppi@isc.cnr.itc© Societa` Italiana di Fisica 5960 F. GRAZZI, M. CELLI, S. SIANO and M. ZOPPIby an almost total disengagement from any research activity in the nuclear energy field,after the Chernobyl accident.In spite of this unfortunate situation, the role of CNR (Consiglio Nazionale delleRicerche) has been of fundamental importance to partially compensate for this handicap.Since the mid 80’s, a collaboration was started with the Rutherford Appleton Laboratory(RAL, UK), where a new generation pulsed neutron source (ISIS) was under construction.The building of the PRISMA spectrometer, by ISM-CNR during the period 1985-1995,and the following realization of the TOSCA spectrometer, by IEQ-CNR in the period1996-2002, has witnessed a steady growth, both in qualitative and quantitative terms, ofthe Italian neutron scattering community. Today, thanks to the joint efforts of CNR andthe former INFM (now merged into CNR) the Italian neutron community has reached alevel of maturity that compares well with other countries in the European Union.The idea of realizing an Italian experimental station at the world most powerful pulsedneutron source (ISIS, UK) is rather old and has been circulating among the membersof the CNR Neutron Spectroscopy Advisory Committee for several years. However, itwas only after the realization of the TOSCA spectrometer that this project could befinalized on a more concrete ground. The Italian Neutron Experimental Station (INES)was planned as a general-purpose facility, to be mainly used for testing of equipment,training, and development of neutron scattering techniques. It is worthwhile mentioningthat the Committee, evidencing the importance that such a Test Station would assume inthe applied sciences (Chemistry and Materials Science, Earth Sciences, Crystallography,etc.), had explicitly required that INES should be equipped with a neutron diffractioninstrument. The project has been totally financed by the Italian Consiglio Nazionale delleRicerche and was developed by a team of CNR researchers, in strict cooperation withseveral academic experts. At present, the construction and testing activity is concludedand the Italian Neutron Experimental Station is available for the whole Italian scientificcommunity.It is widely recognized that neutron diffraction is a very important tool for solvingproblems in condensed matter physics, chemistry and materials science. In particular,neutron diffraction plays an important role in technological problems where the localiza-tion and the quantitative measurement of residual stresses and strains can influence theperformances of manufacts. In addition, the most recent techniques of data analysis (e.g.,Rietveld refinement applied to quantitative phase analysis and microstructure solutionusing the MAUD package) allow for a generalized qualitative and quantitative investi-gation of the samples. Finally, we should never forget that neutrons are characterizedby a weak cross-section, at the atomic level, and therefore their penetration depth caneasily reach several cm in almost all materials, including metals. This makes neutronsan almost ideal probe for non-invasive, non-destructive evaluation of the microscopicbulk features of almost any material. In this field, apart from the obvious technologicalapplications, and the well-known diagnostic techniques in material science, another veryimportant use of neutron diffraction is in the field of science applied to the study ofcultural-heritage artefacts.In general, the discovery and the detailed study of an ancient object or manufactoriginates a variety of problems that can be broadly grouped in two categories. First, oneshould determine the cultural and historical framework in which the object was produced.Second, it is crucial to determine the best conservation and/or restoration method. Inthis context, a careful material characterization analysis is of fundamental importance. Inaddition, this can be of great help in understanding the ancient manufacturing techniques,as well as the commercial and human exchanges between contemporary cultures. SeveralPRELIMINARY RESULTS OF THE ITALIAN NEUTRON EXPERIMENTAL STATION INES ETC. 61chemical, physical, and microstructural analysis techniques are available, with some ofthem less invasive than others. Among these, spectroscopic techniques using photons(e.g., X-rays) or elementary particles (e.g., neutrons) assume a relevant role thanks totheir intrinsically non-destructive character. While the use of X-ray diffraction is quitediffuse in research laboratories, neutron diffraction is a relatively new technique that onlyrecently has been applied to volume analysis of cultural-heritage manufacts [1, 2].2. – Instrument descriptionINES is located on the N8 neutron beamline of ISIS, 22.8 m apart from the watermoderator, downstream the inelastic spectrometer TOSCA. The neutron beam emergingfrom TOSCA is collimated to give a uniform square cross-section, of  38 mm size, atthe INES sample position. The station is equipped with its own beam shutter so thatthe two instruments can operate almost independently from each other. On average,the samples measured on TOSCA remove between 5 and 10% of the neutron beam.Thus, INES can use between 90 and 95% of the nominal beam. The instrument isequipped with a time-of-flight (TOF) neutron diffractometer. In the actual configuration(see fig. 1), the diffractometer is equipped with 144 3He squashed detectors, groupedin 9 banks, each composed by 16 detectors, covering a range of about 160◦ on thehorizontal scattering plane. The sample container is such that any ISIS standard sampleenvironment equipment (i.e. furnaces and cryostats) can be placed in the instrument.That is made by a large vacuum tank (80 cm diameter and  0.5 m3 effective volume)that allows the study of large objects, including bulky archaeological artifacts. In addition,this is equipped with four optical windows, where web cameras can be adapted for a visualinspection of the sample during the experiment. A diode laser device is also available,to visualize the center of the incident neutron beam, when using irregular samples [3].Test measurements have shown that the instrumental features, in terms of countingefficiency and resolution, are extremely appealing and in full agreement with the designcharacteristics.In table I, the main features of the TOF diffractometer are summarized. As we men-tioned before, the primary flight path is rather long (L0 = 22.8 m) and determines thegood resolving power of the instrument. The minimum and maximum neutron wave-lengths available on INES (λmin and λmax) are reported in the table caption. The re-sulting interval is mainly determined by the aperture and closure times of the nimonicchopper that is placed upstream the TOSCA spectrometer to reduce the noise effectsproduced by the fast neutrons. However, the actual selection of the recording TOF in-terval is chosen taking also into account the frame-overlap effect at the sample positionof INES. The interval of momentum transfer (and d-spacing) that is available for eachdetector is also determined by the scattering angle 2θ according to the relationsQ =4πλsin θ,(1)d =2πQ.(2)A selected sample of these intervals is illustrated in the table. We observe that a wideextension of momentum transfer (h¯Q) and inter-plane spacing (d) is available using thewhole set of 144 detectors. As we mentioned before, these are grouped in 9 banksand, usually, data analysis would produce 9 independent diffraction patterns at different62 F. GRAZZI, M. CELLI, S. SIANO and M. ZOPPIFig. 1. – Schematic drawing of INES. The neutron beam enters from the right and the sampleposition is placed in the center of the figure. The nine detector banks are placed on a 100 cmradial position, covering an interval of scattering angles from 10◦ to 170◦. The 80 cm diametersample tank is also sketched. The upper half of the available space, on the right of the neutronbeam, has been left free for testing of equipment and development of neutron instrumentation.(nominal) scattering angles. This would allow to make texture analysis quick and easy.However, it is also possible to analyze the 144 patterns separately, at the expenses of amuch longer acquisition time.3. – Preliminary resultsDuring the commissioning of the instrument, a careful calibration was carried outusing a silicon powder sample (Si 640 C) in a vanadium container of 8 mm diameter.The Bragg peaks of silicon were reproduced with an accuracy better than 0.1%, oneach detector, thus allowing for a very precise calibration of the secondary path and thescattering angles. The overall scattering throughput was measured using a cylindricalvanadium sample (10 mm diameter) and compared to a calculation based on the inputmonitor counting rate. For the calculation, we have taken into account all the geometricand technical characteristics of the instrument as well as the dimensions and shape of thesample. The results are shown in fig. 2 and evidence the good accuracy in the definitionof all the instrumental parameters.A polycrystal sample, characterized by a random and uniform distribution of pre-ferred orientation regions is said to be free of texture. On the contrary, when regionsshowing preferred orientation of crystallites are observed, the sample is said to be tex-tured. Texture is an important characteristics of metals, alloys, and ceramics. This isthe result of the solidification process and therefore represents an important signature ofthe sample manufacturing history.A preliminary test, aiming to evidence the possibility of performing texture analysisPRELIMINARY RESULTS OF THE ITALIAN NEUTRON EXPERIMENTAL STATION INES ETC. 63Table I. – INES main parameters: The neutron beam originates from the water moderator ofISIS. A NIMONIC chopper is located at 9.60 m from the moderator, to filter out the high-energyneutrons. This opens at tmin = 724 μs and closes at tmax = 10, 339 μs (time is measuredassuming that the proton beam hits the spallation target at t = 0) and selects the neutronwavelength interval (λmin = 0.17 A˚, λmax = 3.24 A˚). The primary neutron path at sampleposition is L0 = 22.804 m, while the secondary path is L1 = 1.000 m. In the table we reportthe data relative to the first detector of each bank (A-1, B-1, · · · , I-1) plus the last detector ofthe last bank (I-16). The resolution Δd/d (HWHM) has been measured on the Bragg peak atd = 1.6375 A˚ of the silicon powder sample.Detector label 2θ (◦) Qmin (A˚−1) Qmax (A˚−1) dmax (A˚) dmin (A˚) Δd/dA-1 170.6 3.85 62.62 1.63 0.10 0.0012B-1 152.6 3.76 61.04 1.67 0.10 0.0012C-1 134.6 3.57 57.96 1.76 0.11 0.0013D-1 116.6 3.29 53.45 1.91 0.12 0.0015E-1 98.6 2.93 47.62 2.14 0.13 0.0017F-1 80.6 2.50 40.62 2.51 0.15 0.0020G-1 62.6 2.01 32.63 3.13 0.19 0.0025H-1 44.6 1.47 23.82 4.29 0.26 0.0035I-1 26.6 0.89 14.44 7.07 0.44 0.0056I-16 11.6 0.39 6.33 16.13 0.99 0.01300,0 0,5 1,0 1,5 2,0 2,5 3,0 3,50,05,0x1041,0x1051,5x1052,0x1052,5x1053,0x1053,5x105Counts/Åneutron wavelength (Å)Fig. 2. – Comparison between measured spectrum N.16 (dots), and the one calculated usingthe geometric and technical characteristics of the instrument (line). The sample is a vanadiumrod (10 mm diameter) while the distribution of the incident neutron flux is obtained from thecalibrated input monitor.64 F. GRAZZI, M. CELLI, S. SIANO and M. ZOPPI1,0 1,2 1,4 1,6 1,8 2,0 2,2  2θ=105.6o1,0 1,2 1,4 1,6 1,8 2,0 2,22θ=87.6o1,0 1,2 1,4 1,6 1,8 2,0 2,22θ=70.6o1,0 1,2 1,4 1,6 1,8 2,0 2,2intensity (a.u.)2θ=51.6od spacing (Å)Fig. 3. – Measured texture of a Roman age bronze coin (average acquisition time  1 hour). Inthe figure, we show four diffraction patterns, taken by four different detectors chosen at selectedscattering angles. The large intensity variation of the various Bragg peaks is clearly visible.of the samples, has been carried out on two different bronze sheets containing 2% and 4%(weight) tin, respectively. The sheets were prepared by mechanical rolling and strainingalong one axis. This produces a forced preferential orientation of the surface crystallitesalong the rolling direction. Measurements were performed with the beam axis perpen-dicular to the rolling plane and rotating the samples along the beam axis (φ). In spiteof the weak texture level produced by this sample preparation method, we were able toobserve, on both samples, a clear effect in the measured diffraction patterns both alongthe detector angle (θ) and along the sample rotation angle (φ).A critical test of the instrument was performed using a Roman age bronze coin. Thiswas oriented perpendicular to the beam and spectra were taken applying several rotationsto the sample, around the beam axis, up to a final angle φ = 180◦. Thus, we were able toobtain a rather satisfactory mapping of the whole solid angle in less than 4 hours, withthe possibility to obtain a full range of polar figures for all the peaks of interest. As anexample, the potentials of the INES diffractometer are shown in fig. 3, where the hightexture level of the Roman coin is clearly visible on four different diffraction patternstaken at various angular positions. In order to speed up measurement time and to obtaina more precise control on the sample rotation, a new automatic rotating device is underconstruction. This will permit to rotate small samples around the neutron beam axis andto obtain a full polar figure in a relatively short time (between 3 and 10 hours, dependingon the scattering power of the sample).The polar figure of a textured object represents the map of the crystallites domainorientation. This is a fingerprint of the production technique and can be of great help infollowing the historical evolution of the manufacturing techniques. Last, but not least, agood polar figure could be potentially used to distinguish a genuine archaeological objectfrom a copy.PRELIMINARY RESULTS OF THE ITALIAN NEUTRON EXPERIMENTAL STATION INES ETC. 654. – ConclusionsThe high penetration power of thermal neutrons into dense objects makes neutrondiffraction a non-invasive, non-destructive, technique allowing one to obtain microscopicstructural information, integrated over the scattering volume of the sample. This featureis particularly important for bulky metal manufacts of archaeological origin. The positionof Bragg peaks gives a detailed information on the interplane distance at the atomic levelwhich can provide information on residual stresses and strains and represent a signatureof thermal history of the sample. In addition, texture analysis provides information on thepreferred orientation distribution of crystal domains in the material. This knowledge canbe of fundamental importance in corroborating or invalidating proposed manufacturingtechniques.At present, the INES experimental neutron station is equipped with a general pur-poses diffraction instrument allowing to measure any kind of standard samples, in anextended range of temperatures, with a very good resolution (see table). The wide sam-ple chamber permits measurements on almost any kind of objects, even rather large andwith irregular shapes such as, for example, industrial specimens and artefacts of historicalinterest. These can be carefully positioned into the neutron beam by visual inspectionof the target position using a laser beam and a web camera. The scattered neutrons arecollected by nine detector banks, each composed by sixteen elements of squashed 3Hetubes. The possibility of analyzing the signal from each single detector, coupled withthe planned rotating device, will permit to obtain a full coverage of the scattering solidangle and the reconstruction of polar figures for almost any kind of samples. Thanks tothese characteristics, INES can candidate itself as one of the most interesting neutrondiffraction instruments for cultural-heritage samples.∗ ∗ ∗The authors whish to thank the continuous support of Consiglio Nazionale delleRicerche for the realization of this project. In particular, the Cooperation AgreementNo. 01/9001 between CNR and CCLRC, concerning collaboration in scientific researchat the spallation neutron source ISIS (UK) is gratefully acknowledged. We acknowledgethe skillful support of the ISIS staff during the construction and commissioning phasesof the instrument. Special thanks go to J. Tomkinson, B. Holsman, P. Radaelli,W. Kockelmann, N. Rhodes, E. Schooneveld, K. Allum and K. J. Knowles,for their continuous support and assistance. Stimulating discussions with U. Bafile,D. Colognesi, S. Imberti and F. Sacchetti are gratefully acknowledged.REFERENCES[1] Kockelmann W., Kirfel A. and Ha¨hnel E., J. Archaeol. Sci., 28 (2001) 213.[2] Siano S., Kockelmann W., Bafile U., Celli M., Iozzo M., Miccio M., Moze M.,Pini R., Salimbeni R. and Zoppi M., Appl. Phys. A, 74 (2002) S1139.[3] For a detailed description of the INES experimental station see: Celli M., Colognesi D.,Grazzi F., Zoppi M., Checchi C. A. and Schooneveld E., Notiziario Neutroni e Lucedi Sincrotrone, 10 (2005).

Preliminary results of the Italian neutron experimental station INES at ISIS: Archaeometric applications

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Preliminary results of the Italian neutron experimental station INES at ISIS: Archaeometric applications

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