advertisement

2006 Radicarbon History

53 %
47 %
advertisement
Information about 2006 Radicarbon History
Entertainment

Published on October 16, 2007

Author: CoolDude26

Source: authorstream.com

advertisement

HISTORY OF RADIOCARBON DATING:  HISTORY OF RADIOCARBON DATING ORIGINS: Willard F. Libby (1908-1980) 1. 1927-1940 Libby at UC Berkeley: In the Beginning 2. 1940-1945 Libby at Columbia: The War Years 3. 1945-1952 Libby at Chicago: Three Critical Experiments DEVELOPMENT 4. 1952-1960 First Radiocarbon Revolution 5. 1960-1980 Second Radiocarbon Revolution: Calibration 6. 1980- Third Radiocarbon Revolution: AMS 1927-1940 Libby at Berkeley :  1927-1940 Libby at Berkeley In the Beginning . . . Undergraduate (Chemistry): 1927-1931 » Graduate (Physical Chemistry): 1931-1933 Early 1930s: 14C = a “minor radioisotope” assumed short half life (< 1 year) artificially produced before detected in nature recoil tracks used to calibrate cloud chamber experiments favored production mechanism: deuterons [nuclei of deuterium, an isotope of hydrogen] on 13C 1927-1940 Libby at Berkeley:  1927-1940 Libby at Berkeley Ernest O. Lawrence 1939 Nobel Prize in Physics 14C: “A radioisotope with biomedical promise” long half life (>1000 years) favored production mechanism: neutrons on 14N 1927-1940 Libby at Berkeley:  1927-1940 Libby at Berkeley Serge A. Korff (New York University) cosmic ray physics experiments increase in neutrons with increasing altitude neutrons created by cosmic rays natural atmospheric 14C production by neutron secondaries Korff and Danforth (1939) Physical Review 1927-1940 Libby at Berkeley:  1927-1940 Libby at Berkeley UCB Ph.D. (1933) nuclear chemistry Built first Geiger counter » in U.S. Dissertation: Weak beta » activity in rare earth elements Known at UCB as "Wild Bill Libby" for pushing "far out" ideas 1927-1940 Libby at Berkeley:  1927-1940 Libby at Berkeley Screen-wall counter design: problem of detecting betas close to background » counter envelope glass wire grid (“screen-wall”) cathode: define sensitive volume sample applied to inside surface of glass sleeve glass sleeve moved in and out of sensitive volume mechanical mechanism for alteration of » background and sample counting Basic design of detector used in post World War II 14C experiments 1927-1940 Libby at Berkeley:  1927-1940 Libby at Berkeley Late 1930s: 14C half life >1000 years (103-105 years) Favored production: neutrons on 14N Libby reads Korff and Danforth (1939) Libby: “That’s » Radiocarbon Dating!” 1927-1940 Libby at Berkeley:  1927-1940 Libby at Berkeley Radiocarbon dating: Basic physical model (1939) production in atmosphere as 14CO2 photosynthetic fixing in biosphere living biosphere 14C equilibrium death withdrawal from exchange time since death function of residual 14C concentration No experimental confirmation 1940-1945 Libby at Columbia: The War Years:  1940-1945 Libby at Columbia: The War Years Research on hold during World War II. 1940-1945: Manhattan Project With Harold Urey [1934 Nobel Prize in chemistry] at Columbia University developing a thermal diffusion method to separate 235U from 238U later thought this research as the high point of his scientific career Requested 14C half-life measurement at Argonne: 26,000± 13,000 and 21,000± 4000 years 1945-1952 Libby at Chicago: Three Critical Experiments:  14C: A dating isotope? Testing implications of model 1946-1952: University of Chicago With Harold Urey in the Institute of Nuclear Studies Libby (1946) Physical Review: first published description of concept: coined term "radiocarbon" With first Chicago graduate student Ernest C. Anderson: First Critical Experiment: isotopic enrichment documented difference in 14C activity between modern biomethane and fossil petromethane 1945-1952 Libby at Chicago: Three Critical Experiments 1945-1952 Libby at Chicago: The Critical Experiments:  1945-1952 Libby at Chicago: The Critical Experiments 14C: A dating isotope? Testing implications of model James Arnold joins group as » Postdoctoral Fellow Decay counting using solid » carbon in a modified Geiger counter of Libby's Berkeley design Critical technical development: Electronic anticoincidence » shielding for low level counting close to background Made decay counting 14C dating practical Second Critical Experiment: Anderson dissertation: 14C activities in living samples from various latitudes were » essentially equal (exception: marine shell) 1945-1952 Libby at Chicago: The Critical Experiments:  1945-1952 Libby at Chicago: The Critical Experiments 1947-48: Third Critical experiment First 14C date: wood from tomb of Zoser (Djoser), 3rd Dynasty Egyptian king (July 12, 1948). Historic age: 4650±75 BP Radiocarbon age: (C-1) 3979±350 BP [average of 3 determinations 3699±770, 4234±600, 3991±500] Second 14C date: wood from Hellenistic coffin Historic age: 2300±200 BP Radiocarbon age: (C-?) Modern! Fake! First “Curve of Knowns”: 6 data points (using seven samples) spanning AD 600 to 2700 BC. Half life used: 5720± 47 years 1945-1952 Libby at Chicago: The Critical Experiments:  1945-1952 Libby at Chicago: The Critical Experiments 1948: Adaption of screen-wall counter design using elemental (solid) carbon CO2 from combustion/acidification reduced by reaction with magnesium at high temperature and separation of MgO ("ash") from elemental carbon ("lamp black") by treating with concentrated HCl. Inside surface of sleeve of screen-wall counter coated with elemental carbon: The Procedure from Hell! Construction of large scale (3 story high) thermal diffusion column in case routine screen-wall counter operation not achieved; column never used Destruction of set of counters when crushed under weight of magnets of new accelerator being installed 1945-1952 Libby at Chicago: The Critical Experiments:  1945-1952 Libby at Chicago: The Critical Experiments 1949: Critical Experiments Successful “The agreement between prediction and observation is seen to be satisfactory." Average overall errors on ages = ±10% Foundation 14C paper: Arnold and Libby "Age determinations by radiocarbon content: checks with samples of known age." Science, December 23, 1949. Birthday of Radiocarbon Dating 1945-1952 Libby at Chicago :  1945-1952 Libby at Chicago Chicago Radiocarbon Laboratory operational: 1949-1952 554 samples measured and published in a series of “date lists.” First Chicago list (September 1, 1950): 148 14C dates. » Published with minor modifications in Science in February 1951 (Arnold and Libby 1951) using new “Libby half life” = 5568±30 yrs. First Revised "Curve of Knowns" substituted Libby t1/2 1952-1960 First Generation Labs :  1952-1960 First Generation Labs Libby appointed to Atomic Energy Commission (1952) 1st International Radiocarbon Conferences: Copenhagen and Andover (1954). [No proceedings published until 6th in Pullman 1965] Second Revised "Curve of Knowns" had eleven data points » included "Bible" [(wrappings from Dead Sea Scrolls] (Libby, Radiocarbon Dating, 2nd edition, 1955) First Generation (solid carbon) Labs: Arizona*, Michigan*, Pennsylvania,* Yale, Lamont (Columbia), New Zealand, Copenhagen, Saskatchewan. [* archaeologists instrumental in establishing] 1952-1960 First Generation Labs:  1952-1960 First Generation Labs Obsolescence of solid carbon: nuclear fallout. » Conversion to or development of gas proportional and » liquid scintillation counting labs: e.g., U.S.G.S., Scripps (UC San Diego), Groningen, British Museum, Cambridge, Stockholm, Uppsala 1959: Journal Radiocarbon begins publication as annual Radiocarbon Supplement to American Journal of Science publishing date lists, separate standing as Radiocarbon from 1963. From 1989, Radiocarbon: An International Journal of Cosmogenic Isotope Research 1960: Nobel Prize in Chemistry: "for his method to use Carbon-14 for age determinations in archaeology, geology, geophysics, and other sciences." Libby had arrived at UCLA in late 1959, established Isotope Laboratory in Institute of Geophysics and Planetary Physics 1960 Nobel Prize in Chemistry:  1960 Nobel Prize in Chemistry 1960-1980 “Second Radiocarbon Revolution:” Calibration :  1960-1980 “Second Radiocarbon Revolution:” Calibration Calibration: Violation of assumption of constant biospheric "zero age" 14C activity First test: 1949: First “Curve of Knowns”: "satisfactory agreement" to 5000 BP with overall precision of ±10% Increased counting sensitivities: 1960: additional Egyptian Old Kingdom (ca. 3000-2100 BC) samples "too young" by 500-600 yrs at 3000 BC. Libby (1963) suggested that conventional reconstruction of ancient Egyptian chronology by contemporary Egyptologists was in error rather than 14C-inferred ages. First detailed study: 1960: Using tree ring series and » proportional gas counters with ±1% (±80 yrs) counting variances. Existence of systematic offsets of up to about 160 years over last 1300 years. 1960-1980 “Second Radiocarbon Revolution:” Calibration :  1960-1980 “Second Radiocarbon Revolution:” Calibration Calibration of 14C time scale: Distinguishing “real (solar, sidereal) time" and "14C time” Bristlecone pine / 14C data: First detailed continuous tree ring- » based data set documenting 14C offsets over last 7000 yrs. (Sues » 1970). Documents: (1) major or long-term trend (apparent sine- wave function) and (2) complex set of shorter-term/higher- frequency variations. Long-term anomaly: maximum Holocene offset about 10% or » 800 years at about 7000 BP Shorter-term anomalies: “De Vries effects” multi-millennial » and multi-century oscillations in 14C time spectrum ("wiggles," "kinks," "warps") = accordion-like characteristics of 14C time scale. At some time periods in Holocene, 14C time resolution is inherently temporally "blinded" for various intervals irrespective of counting variance on sample measurement. 1977 Conventional Radiocarbon Age: Definition :  1977 Conventional Radiocarbon Age: Definition Stuiver and Polach (1977) Reporting of 14C Data. Radiocarbon 1. Use Libby half-life (5568 years) 2. Use 0.95 NBS Oxalic Acid I [or standards with known relationship] to define “zero” age 14C count rate 3. Use A.D. 1950 as 0 BP. [BP = “Before Physics”] 4. Normalize 14C activity to common δ13C value = -25.0 ‰ 5. Uncalibrated Defines “radiocarbon time” expressed in “14C years” 1980-present Third Radiocarbon Revolution: AMS:  1980-present Third Radiocarbon Revolution: AMS Pre-AMS 1970: Late Hans Oeschger (Bern) first noted great » increase in sensitivity that would be possible from ion counting using isotopic enrichment and mass spectrometry. 1974-77: Michael Anbar [SUNY Buffalo] (1978) reports an effort undertaken earlier at Stanford Research Institute to use conventional mass spectrometry to measure CN- for natural level 14C detection. Backgrounds from mass 29 trace impurities prevented the approach from becoming feasible for routine work. Ran out of funds. 1970-1980 Third Radiocarbon Revolution: AMS:  1970-1980 Third Radiocarbon Revolution: AMS Cyclotron AMS 1976-1977: Richard Muller [UC Berkeley] (1977) examined a cyclotron-based AMS technique, principle of using particle accelerator charge-to-mass filter first demonstrated by Luis Alvarez in 1939 in detecting 3He. Berkeley "high energy mass spectrometry" (HEMS) » combined cyclotron for mass resolution and range » separation of 14N from 14C using a xenon cell. Suggested extension of 14C time frame to 106 years with AMS if contamination free sample could be prepared. First published AMS-based 14C date. » 1980's: Muller's group unsuccessful attempt to develop a 40 » keV "cyclotrino" for routine 14C measurements using external ion source. (Shanghai group successful in 1990s) 1977-1980 Third Radiocarbon Revolution: AMS:  1977-1980 Third Radiocarbon Revolution: AMS Tandem AMS 1977: Rochester-Toronto-General Ionex (Purser et al.) ° and Simon Frazer-McMaster (Nelson et al.) groups essentially simultaneously employed tandem accelerators using negative ions to detect natural level 14C. History of science footnote: Harry Gove (Rochester group) argues that "Rochester Tandem experiment produced the first ever carbon-14 date by accelerator mass spectrometry, since we made a background measurement on graphite. The work at Rochester had been carried out two weeks before that at McMaster but they beat us by one day in getting their manuscript to the publisher [Science].” 1978: First Conference on Radiocarbon Dating with Accelerators, University of Rochester. Initial AMS spectrometers previously used for nuclear » structure, refitted for AMS work. First dedicated AMS » instrument: University of Arizona. » Radiocarbon Dating Impact: Archaeology:  Radiocarbon Dating Impact: Archaeology 1948-1970 “First Radiocarbon Revolution” ° 14C dating constitutes the “great revolution in 20th century prehistoric studies” Glyn Daniel Development of 14C dating in 20th century comparable to discovery of antiquity of the human species in the 19th century Made a world-wide chronometric framework for prehistory possible Radiocarbon Dating Impact: Archaeology Chronology of the Peopling of the New World :  Radiocarbon Dating Impact: Archaeology Chronology of the Peopling of the New World Advent of 14C dating transformed approaches to the dating frameworks for Paleoindian and Paleoamerican studies History of the application of 14C data in Paleoindian / Paleoamerican contexts provide classic case studies of some of the issues and problems encountered in the critical application of the 14C method Chronology of the Peopling of the New World:  Chronology of the Peopling of the New World Folsom sites 14C age BP _____________________________ Hanson (4) 10,290±90 Carter/Kerr McGee 10,400±600 Lubbock Lake 10,540±100 Indian Creek/1 10,630±280 Owl Cave 10,640±85 Lindenmeier (3) 10,660±60 Agate Basin (2) 10,700±70 Folsom (6) 10,890±50 Indian Creek/2 10,980±150 [20 14C values from 8 sites] Chronology of the Peopling of the New World:  Chronology of the Peopling of the New World Clovis sites 14C age BP __________________________________ Murray Springs (8) 10,890±50 Lehner (12) 10,940±40 Anzick 10,940±90 Dent 10,980±90 UP Mammoth 11,280±350 Lange/Ferguson 11,140±140 Colby 11,200±220 Domebo 11,480±450 Blackwater Draw(3) 11,300±240 Aubrey (2) 11,570±70 [31 14C values from 10 sites] Radiocarbon Dating Impact: Archaeology Chronology of the Peopling of the New World:  Radiocarbon Dating Impact: Archaeology Chronology of the Peopling of the New World Initial Data Tule Springs, Nevada: >23,800 14C years BP (C-914) on what was characterized as charcoal recovered from what had been identified as a "hearth-like feature" by excavators who associated its occurrence with sediments containing the bones of extinct Pleistocene fauna [1953] Old Crow, Yukon Territory, Canada: 27,000+3000/-2000 14C years BP (GX-1640) on an inorganic fraction ("bone mineral apatite") of a bone artifact [1973] Radiocarbon Dating Impact: Archaeology Chronology of the Peopling of the New World:  Radiocarbon Dating Impact: Archaeology Chronology of the Peopling of the New World Revised Data Tule Springs: "charcoal" determined to be decayed plant remains and "hearths" determined to be water channel or spring deposit structures. Oldest artifact(s): 10,000-11,000 14C years BP based on over 100 14C dates from site [1974] Old Crow: an organic fraction of the bone artifact yielded an age of 1350±150 14C years BP (RIDDL-145) [1986] Radiocarbon Dating Impact: Archaeology Chronology of the Peopling of the New World:  Radiocarbon Dating Impact: Archaeology Chronology of the Peopling of the New World Radiocarbon Dating Impact: Archaeology Chronology of the Peopling of the New World:  Radiocarbon Dating Impact: Archaeology Chronology of the Peopling of the New World Radiocarbon Dating Impact: Archaeology Chronology of the Peopling of the New World:  Radiocarbon Dating Impact: Archaeology Chronology of the Peopling of the New World skeleton 14C values (BP) reference _____ Tlapacoya I, Mexico 10,200±65 Gonzalez et al. 2003 Arroyo Frias, Argentina 10,300±60 Hicks, per. comm. 1995 Buhl, Idaho 10,675±95 Green et al. 1998 Peñon III, Mexico 10,775±75 Gonzalez et al. 2003 Anzick, Montana 10,940±90 Stafford et al. 1991 Arlington Springs, California 10,960±80 Johnson et al. 2000 Naharon I, Mexico 11,670±60* unpublished ______________________________________________________________ * 14C measurement on non-collagen-like amino acids; minimum age (?) Radiocarbon Dating Impact: Archaeology Chronology of the Peopling of the New World:  Radiocarbon Dating Impact: Archaeology Chronology of the Peopling of the New World Kennewick, Washington human skeleton Sample bone bone fraction 14C age (BP) δ13C(‰) preservation _______________________________________________________________________ 5th left metcarpal 68.8%(C)1 TAA3 8410±605 -14.9 1st right metacarpal 0.3%2 BETAI4 8410±406 -12.6 1st right metacarpal 14.3%(NC)1 TAA3 8130±405 -10.8 Left tibial crest 2.3%(NC)1 TAA3 6940±305 -10.3 Left tibial crest 0.05%2 gelatin 5750±1007 -21.9 _______________________________________________________________________ 1% of modern bone standard amino acid content, C= collagen-like amino acid composition. 2percent carbon yield. 3 TAA = total amino acid. 4 Base extracted acid insoluble. 5 UC Riverside sample prep/Lawrence Livermore National Laboratory AMS measurement. 6 Beta Analytic. 7 University of Arizona accelerator Radiocarbon Dating Impact: Archaeology:  Radiocarbon Dating Impact: Archaeology Radiocarbon dating continues to be the “gold standard” for assigning age to Holocene and late Pleistocene archaeological, geological, and paleontological contexts Late UCB Prehistorian J. Desmond Clark: Without the 14C time scale, prehistorians would be “foundering in a sea of imprecisions sometimes bred of inspired guesswork but more often of imaginative speculation.” end

Add a comment

Related presentations

Related pages

Radiocarbon dating - Wikipedia, the free encyclopedia

Radiocarbon dating (also referred to as ... History In the early 1930s, ... Maslin, Mark A.; Swann, George E.A. (2006). "Isotopes in marine sediments". In ...
Read more

Radiokarbonmethode – Wikipedia

... The remarkable metrological history of radiocarbon dating ... Bd. 439, Nr. 7079, 2006, S. 931–935, doi: 10.1038/nature04521. Gerhard Morgenroth: ...
Read more

Radiocarbon 14 dating of the Shroud of Turin - Wikipedia ...

Radiocarbon 14 dating of the Shroud of Turin. The Shroud of Turin (Turin Shroud), a linen cloth that tradition associates ... History 1978: the creation of ...
Read more

K-12 - radiocarbon WEB-info

Welcome to the K12 section of the Radiocarbon ... able to interpret and understand history? Before 1950, when radiocarbon dating was first ...
Read more

Radiocarbon Calibration - Fairbanks Research

Professor Richard G. Fairbanks. ... C content of the atmosphere and oceans contain a remarkable array of information about Earth history. ... 2006), Reimer ...
Read more

Lost tsunami - Pareschi - 2006 - Geophysical Research ...

First published: 28 November 2006 Full publication history; ... Radicarbon, 33, 15 ... (2006) modeled this ...
Read more

Geographical extremes in the glacial history of northern ...

Geographical extremes in the glacial history of northern Eurasia: post-QUEEN considerations Valery Astakhov Geological Faculty, St. Petersburg University ...
Read more

The Isbister Cairn - The Tomb of the Eagles - Sigurd Towrie

History Tradition Folklore ... Downloads About the Site Contact Links Search Site Awards : The Isbister Cairn - The Tomb ... Radicarbon dates ...
Read more