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Embedding radioactive materials into low-temperature microcalorimeters Some preliminary ideas and results Michael W. Rab

Embedding radioactive materials into low-temperature microcalorimeters Some preliminary ideas and results Michael W. Rabin Los Alamos National Laboratory

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Embedding radioactive materials into low-temperature microcalorimeters Some preliminary ideas and results Michael W. Rab

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  1. Embedding radioactive materials into • low-temperature microcalorimeters • Some preliminary ideas and results • Michael W. Rabin • Los Alamos National Laboratory • D.A. Bennett4, E. Birnbaum1, E.M. Bond1, R.C. Cantor5, M.P. Croce1, J.E. Engle1, F. Fowler4, R.D. Horansky2, K.D. Irwin, K.E. Koehler1,3, G.J. Kunde1, W.A. Moody1, F.M. Nortier1, D. Schmidt2, W.A. Taylor, J.N. Ullom2, L.R. Vale2, M. Zimmer, M.W. Rabin1 • 1Los Alamos National Laboratory, Los Alamos, NM, USA • 2National Institute of Standards and Technology, Boulder, CO, USA • 3Western Michigan University, Kalamazoo, MI, USA • 4University of Colorado, Boulder, CO, USA • 5Star Cryolectronics, Santa Fe, NM, USA Revised Feb 6, 2013

  2. Energy resolution for X- and g-ray spectroscopy Factor of ten better than conventional semiconductor technology

  3. Close look at spectrum for X/g NDA of Pu (102.98) (98.95) 241Pu/ (101.06) (99.85) (104.23) (103.73)

  4. Quantitative analysis of isotopic composition Preliminary results from internal “round robin”—3 sensors X 4 samples Microcalorimeter Conventional sensor Atom ratio comparison for spectrum shown Mcal 0.132 ± 0.006 TIMS 0.133 ± 0.003

  5. External vs. internal for a-decaying isotopes Decay products are the alpha particle and the daughter atom External source External source Internal source Internal source

  6. First high-resolution mixed actinide Q spec Shows 3X increase in separation between peak centers 238Pu 241Am

  7. Large microcalorimeter arrays for spectroscopy • + • Embedded radionuclides • + • Isotope production facility

  8. Some radioactive decays of interest a, b, electron capture

  9. Some radioactive decays of interest a, b, electron capture Also work by Loidl (CEA)

  10. Some radioactive decays of interest a, b, electron capture Key linking science issue The chemical form and physical microstructure of the combination of absorber and source affects energy thermalization.

  11. Some possible surrogate isotopes Use for prototyping methods for isotope encapsulation and sensor designs • Isotopes that decay solely by electron capture to the nuclear ground state of a very long lived or stable product (child) isotope. • High Q is OK for prototyping. • Screening is incomplete and not yet detailed enough.

  12. Possible methods of deposition and encapsulation Assuming you start with liquid water-based solution of radioactive material • Drying of water-based solution • you get everything that does not evaporate • coffee-ring effect • mitigated by extremely very small volumes, ~10 picoliter • Electrodeposition • more selective • codeposition of major species (e.g. Cu, Au, Bi) and ultra trace (Fe, Ho) • used for Cu vias in zillions of integrated circuits • Metalurgy • unfavorable phase diagrams • rapid freezing from melt common to quench nonequilibriumconcentration • bonding and diffusion techniques based interface metalurgy(eutectics) • Surface chemistry • controlled atmosphere, temperature, time, substrate • chemical reduction of salts and oxides hard • selective binding to surface with custom ligands

  13. Incorporation of aqueous source and encapsulation • Techniques for analytical picoliter dispensing under development by LANL-HP collaboration • Precise control of dispensed volume, droplet position, and final spot size • Mitigates position-dependent response of sensors • Allows us to control activity per sensor • Control of physical form and chemical composition will affect energy thermalization physics in the sensors

  14. Examples from 55Fe electrodeposition

  15. Recent sensors for ECS of 55Fe

  16. Spectral results ECS of 55Fe commercial 55Fe Taylor-made 55Fe larger absorber Taylor-made55Fe smaller absorber ~54 eV FWHM

  17. Improved spectral results ECS of 55Fe 19 eV s = 5.25 eVl1 = 8.9 eV 2.35 s = 12.4 eVl2 = 47 eV h = 0.37

  18. New sensors designs No membrane. Easier to make. More robust.

  19. Concluding remarks This is the era for wide-ranging experimentation in for embedding radioactive isotopes into sensors. Long-range plans for calorimetric spectroscopy for neutrino mass call for DE = 1-2 eV FWHM A = 1-100 Bq per pixel which have been not yet been shown for any EC-decaying isotope. By prototyping with 55Fe, then 163Ho we mean to try. Large high-resolution arrays + embedded radioisotopes + isotope production

  20. X ga Q b e-

  21. EC • X ga Q b e- Calorimetric electron capture energy spectroscopy combines many of these.

  22. END

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