Berkeley Offline Radioisotope Generator “BORG”

1. Berkeley Offline Radioisotope Generator“BORG” P.K. Gupta J.B. Patin R. Sudowe September 19, 2002

2. 252Cf : The fission fragment source 252Cf: Half-life: 2.638 a Decay modes: 97 % alpha decay 3 % spontaneous fission 4 μg 252Cf  9.56•1015 atoms  ~ 80,000,000 decays / s  ~ 2,400,000 fissions / s Mass-number yields Y(A) vs. mass number A

3. Existing fission fragment collection device “Ms. Piggy” Gases Aerosol Generators Ms. Piggy Gas Chemistry Collection Detection Reactive Gases

4. Overview – Complete setup Gases Aerosol Generators BORG Gas Chemistry Collection Detection Reactive Gases Aqueous Chemistry BORG Long-lived samples

5. Source Specifications • Source consists of 4µg of 252Cf electroplated as oxide on Pt disk. • Dimensions of Pt disk: Diameter = 0.875 inches • Thickness = 0.01 inches • A 6 µm thick Al foil will be used as cover foil. • Additional 6 µm thick Al foil at entrance window for the recoil chamber. • Source Arrangement • 1.) Park position - Position for safe storage of the source when the device is not in use. • 2.) Collection position – Allows for the collection of fission fragments on a removable catcher foil. • 3.) Running position – Short-lived fission products are collected in a recoil chamber and are transported to the experimental setup using an aerosol gas jet.

6. Sketch Movable Piston Additional bore for neutron activation Reaction Chamber Motor Park position Collection of longer lived nuclides Running position

9. Schematic picture

10. Recoil chamber containment Bore for neutron activation Stack of Polyethylene sheets Motor Crank

11. Basic Design • Basic structure: Multiple layers of polyethylene sandwiched between two metal layers and joined by large metal screws. (each polyethylene sheet is 48 X 48 X 1 cm) • Sheets of polyethylene will be machined to incorporate the source, recoil chamber, bore for neutrons and secondary containment • Gases: Multiple inlets for different types of transport gases and reactive gas mixtures. Flow rate and gas composition can be controlled by computer.

12. Design Goals • It should be possible to use various recoil chamber pressures, carrier gases and aerosols (use of piston to vary the height of recoil chamber) • Crank screwed to the source holder • Threaded hole in the source holder to lift it out • A motor for moving the source between the parking, running and collection positions • Easy interchange of components by making the device modular • A bore for neutron activation. • Swage lock fittings for inlet and outlet pipes.

13. Safety • Aluminum foil between source and recoil chamber to prevent contamination. • Crank attached to the source holder will be separated by O-ring seals to prevent spread of contamination. • Safe secondary storage necessary to contain the source during maintenance and cleaning. • Use of O-rings to seal the source completely from the surroundings and selection of suitable material for O-rings that will be placed close to the source in order to prevent damage from radiation. • Storage vessel for the source during cleaning and maintenance

14. Miss Piggy pictures