Perturbed angular correlation: Difference between revisions

Revision as of 01:20, 30 November 2019

Revision as of 18:38, 30 November 2019

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== History and Development ==

[[File:Koinzidenzdetector.png|thumb|right|Coincidence measurement in simplified depiction.]]

PAC goes back to a theoretical work by Donald R. Hamilton <ref>Donald R. Hamilton: On Directional Correlation of Successive Quanta. In: Physical Review. Band 58, Nr. 2, 15. Juli 1940, S. 122–131, doi:10.1103/PhysRev.58.122</ref> from 1940. The first successful experiment was carried out by Brady and Deutsch <ref>Edward L. Brady, Martin Deutsch: Angular Correlation of Successive Gamma-Ray Quanta. In: Physical Review. Band 72, Nr. 9, 1. November 1947, S. 870–871, doi:10.1103/PhysRev.72.870</ref> in 1947. Essentially spin and parity of nuclear spins were investigated in these first PAC experiments. However, it was recognized early on that electric and magnetic fields interact with the nuclear moment,<ref>H. Aeppli, A.S. Bishop, H. Frauenfelder, M. Walter, W. Zünti, Phys. Rev. 82 (1951) 550.</ref>, providing the basis for a new form of material investigation: nuclear solid-state spectroscopy.

Step by step the theory was developed.<ref>J.W. Gardner, Proc. Phys. Soc. (London) A62 (1949) 763.</ref><ref>D.S. Ling, D.L. Falkoff, Phys, Rev. 76 (1949) 1639.</ref><ref>M. Fierz, Helv. Phys. Acta 22 (1949) 489.</ref><ref>J.A. Spiers, Nat. Res. Council Canada, Publ. No. 1925 (1950) Phys. Rev. 80 (1950) 491.</ref><ref>D.L. Falkoff, G.E. Uhlenboeck, Phys. Rev. 79 (1950) 232.</ref><ref>G. Racah, Phys. Rev. 84 (1951) 910.</ref><ref>U. Fano, Nat'l. Bureau of Standards Report 1214; Phys. Rev. 90 (1953)577.</ref><ref>S.P. Lloyd, Phys. Rev. 85 (1952) 904.</ref><ref>K. Adler, Helv. Phys. Acta 25 (1952) 235.</ref><ref>S.R. de Groot, Physica 18 (1952) 1201.</ref><ref>F. Coester, J.M. Jauch, Helv. Phys. Acta 26 (1953) 3.</ref><ref>L.C. Biedenharn, M.E. Rose, Rev. Mod. Phys. 25 (1953) 729.</ref>

After Abragam and Pound <ref>A. Abragam, R. V. Pound: Influence of Electric and Magnetic Fields on Angular Correlations. In: Physical Review. Band 92, Nr. 4, 15. November 1953, S. 943–962, doi:10.1103/PhysRev.92.943</ref> published their work on the theory of PAC in 1953 inlcudingincluding extra nuclear fields, many studies with PAC were carried out afterwards. In the 1960s and 1970s, interest in PAC experiments sharply increased, focusing mainly on magnetic and electric fields in crystals into which the probe nuclei were introduced. In the mid-1960s, ion implantation was discovered, providing new opportunities for sample preparation. The rapid electronic development of the 1970s brought significant improvements in signal processing. From the 1980s to the present, PAC has emerged as an important method for the study and characterization of materials.<ref>Th. Wichert, E. Recknagel: Perturbed Angular Correlation. In: Ulrich Gonser (Hrsg.): Microscopic Methods in Metals (= Topics in Current Physics. Band 40). Springer, Berlin/Heidelberg 1986, {{ISBN|978-3-642-46571-0}}, S. 317–364, doi:10.1007/978-3-642-46571-0_11</ref><ref>Gary S. Collins, Steven L. Shropshire, Jiawen Fan: Perturbed γ−γ angular correlations: A spectroscopy for point defects in metals and alloys. In: Hyperfine Interactions. Band 62, Nr. 1, 1. August 1990, S. 1–34, doi:10.1007/BF02407659</ref><ref>Th. Wichert, N. Achziger, H. Metzner, R. Sielemann: Perturbed angular correlation. In: G. Langouche (Hrsg.): Hyperfine Interactions of Defects in Semiconductors. Elsevier, Amsterdam 1992, {{ISBN|0-444-89134-X}}, S. 77</ref><ref>Jens Röder, Klaus-dieter Becker: Perturbed γ–γ Angular Correlation. In: Methods in Physical Chemistry. John Wiley & Sons, Ltd, 2012, {{ISBN|978-3-527-32745-4}}, S. 325–349, doi:10.1002/9783527636839.ch10</ref><ref>Günter Schatz, Alois Weidinger, Manfred Deicher: Nukleare Festkörperphysik: Kernphysikalische Messmethoden und ihre Anwendungen. 4. Auflage. Vieweg+Teubner Verlag, 2010, {{ISBN|978-3-8351-0228-6}}</ref> B. for the study of semiconductor materials, intermetallic compounds, surfaces and interfaces. Lars Hemmingsen et al. Recently, PAC also applied in biological systems.<ref>Lars Hemmingsen, Klára Nárcisz Sas, Eva Danielsen: Biological Applications of Perturbed Angular Correlations of γ-Ray Spectroscopy. In: Chemical Reviews. Band 104, Nr. 9, 1. September 2004, S. 4027–4062, doi:10.1021/cr030030v</ref>

While until about 2008 PAC instruments used conventional high-frequency electronics of the 1970s, in 2008 Christian Herden and Jens Röder et al. developed the first fully-digitized PAC instrument that enables extensive data analysis and parallel use of multiple probes.<ref>C. Herden, J. Röder, J. A. Gardner, K. D. Becker: Fully digital time differential perturbed angular correlation (TDPAC) spectrometer. In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. Band 594, Nr. 2, 1. September 2008, S. 155–161, doi:10.1016/j.nima.2008.05.001</ref> Replicas and further developments followed.<ref>Matthias Nagl, Ulrich Vetter, Michael Uhrmacher, Hans Hofsäss: A new all-digital time differential γ-γ angular correlation spectrometer. In: Review of Scientific Instruments. Band 81, Nr. 7, 1. Juli 2010, S. 073501, doi:10.1063/1.3455186</ref><ref>M. Jäger, K. Iwig, T. Butz: A user-friendly fully digital TDPAC-spectrometer. In: Hyperfine Interactions. Band 198, Nr. 1, 1. Juni 2010, S. 167–172, doi:10.1007/s10751-010-0201-8</ref>

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== Laboratories ==

The currently largest PAC laboratory in the world is located at [[ISOLDE]] in [[CERN]] with about 10 PAC instruments, that receives its major funding form [[BMBF]]. Radioactive ion beams are produced at the ISOLDE by bombarding protons from the booster onto target materials (uranium carbide, liquid tin, etc.) and evaporating the spallation products at high temperatures (up to 2000&nbsp;°C), then ionizing them and then accelerating them. With the subsequent mass separation usually very pure isotope beams can be produced, which can be implanted in PAC samples. Of particular interest to the PAC are short-lived isomeric probes such as: ^111mCd, ^199mHg, ^204mPb, and various rare earth probes.

== Theory ==

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{{Reflist}}

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[[Category:Nuclear physics]]

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