The Decay of Radiochemistry and The Decay of Don Wiles A short tour - - PowerPoint PPT Presentation

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The Decay of Radiochemistry and The Decay of Don Wiles A short tour - - PowerPoint PPT Presentation

Jan 11, 2023 50 likes •496 views

The Decay of Radiochemistry and The Decay of Don Wiles A short tour through the History of Radiochemistry Canadian Nuclear Society Ottawa, 19 March, 2009 Radium discovery and Development Artificial Radionuclides Nuclear Fission Applications

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The Decay of Radiochemistry

and

The Decay of Don Wiles

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A short tour through the History of Radiochemistry

Canadian Nuclear Society Ottawa, 19 March, 2009

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Radium discovery and Development Artificial Radionuclides Nuclear Fission Applications and new Discoveries What’s Next?

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Early People involved Henri Becquerel Marie Skladowska Pierre Curie André DeBierne

Early Assistants: Bertha Karlik, Elisabeth Rona, Ellen Gleditsch

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Discoveries:

Radiation and its behaviour New elements and their purification Medical uses of radiation

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Later People involved Kasimir Fajans, Fritz Paneth, Frederick Soddy, George de Hevesy

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Radium discovery and Development Artificial Radionuclides Nuclear Fission Applications and new Discoveries What’s Next?

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1932-34 was a time of Major Advance

The Neutron was discovered The Cyclotron invented Nuclear transformations were started Fission was seen but not recognized

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People involved Fermi, Joliot, Hahn

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23Na (n,ã) 24Na 24Mg 238U (n,ã) 239U 239X

They found many ‘isotopes’ In fact, it was nuclear fission!

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Discovery of the Missing Elements

43 Perrier, Segre - 1937 61 Marinski, Glendennin, Coryell - 1945 85 Corson ... Segre - 1940 87 Perey - 1939

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And the creation of new ones

Neptunium: MacMillan, Starke Plutonium: Berkeley, Dubna, Darmstadt Many more (110 now?)

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Meanwhile back at Port Hope

Fractional Crystallization of Radium By Marie Curie’s procedure: Ba(Ra)Br2 / \ Crystals / \ / \ Solution / \ / \/ \ Radium / \ / \ / \/ \ Barium

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The Radiation was Intense

Monday Mornings the quartz crucibles were brown On being calcined, the solid glowed violet The Radium flame test is Red

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DRW Fingerprints

Radium Burn

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Gamma ray energy (keV)

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Radium discovery and Development Artificial Radionuclides Nuclear Fission Applications and new Discoveries What’s Next?

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People Involved Hahn, Meitner, Strassmann Seaborg, Sugarman, Coryell Thode Wilkinson, Harvey, Grummitt, Yaffe

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2

U-235 Fission Products â Decay

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Fission Yields became the order of the day

140I 140Xe 140Cs 140Ba 140La 140Ce

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Fission Yields in U-235

Mass Number

80 90 100 110 120 140 150 1 2 3 4 5 6 7 8 130

Thode Glendenin DRW

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Fission Yields in U-235

Mass Number

80 90 100 110 120 140 150 1 2 3 4 5 6 7 8 130

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Secrecy!! Senator Joseph McCarthy

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Radiochemistry in Norway

Identified Tin-132

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Radiochemistry at Carleton

Fifty years. Several different areas Taught many students

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Radiation Sources:

One would need: Reactors Cyclotrons Neutron Sources

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Radium-Beryllium Photo-neutron sources Sb-124 - Be

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Radium discovery and Development Artificial Radionuclides Nuclear Fission Applications and new Discoveries What’s Next?

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Hot atom reactions became important

What happens to the chemistry of a Newly-radioactive atom?

Too difficult for current experiments and theories

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Mn / | \ C C C O O O Mn / | \ C C C O O O Mn2(CO)10 Mn(CO)5

What is happening?

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Activation Analysis was a Big Thing

in Archaeology Especially with high-resolution Detectors

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But we had a better idea!

Nitrogen in proteins

15N (n,ã) 16N

Reactor neutrons have too high energy:

16O (n,p) 16N

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Use a photoneutron source

9Be (ã,n) 8Be

Using 124Sb, (Eã = 1.76 MeV) the maximum neutron energy would be about 25 KeV. We had the largest neutron source in the world The flux was only 108 Not strong enough

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Mössbauer Spectroscopy became the thing to do

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Gamma Ray

Eã = E - recoil ÄE= h/Ät ÄE Chemical Energies ÄE Doppler Energies

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57Co 57Fe

ÄEÄt = h long life gives precise energy 98 ns, 144 KeV

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Measuring alpha particles became the thing to do

Led to environmental Radiochemistry

Nuclear Waste Disposal

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Radium discovery and Development Artificial Radionuclides Nuclear Fission Applications and new Discoveries What’s Next?

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Synthesis of radiopharmaceuticals Development of new irradiation techniques

(theraspheres)

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Radiochemistry has Changed

Radiochemistry has now become a servant to other fields of study: Pharmaceutical and Medicinal Radiochemistry Environmental Radiochemistry

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Chemistry of fission products in the environment Iodine-129 Chlorine-36 Technetium-99 Others?

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How do we counter public apprehension? Where would one go now To Study in Radiochemistry?

La Dernière Classe

Environmental Radiochemistry?