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…continued from solar neutrino presentation, NESS02, Sept. 2002

…continued from solar neutrino presentation, NESS02, Sept. 2002. 6 papers presented tomorrow morning Many thanks to Wick Haxton for giving us the extra time 14C in deep oilfields Homestake rails as a source of radiopure structural and shielding material.

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…continued from solar neutrino presentation, NESS02, Sept. 2002

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  1. …continued from solar neutrino presentation,NESS02, Sept. 2002 • 6 papers presented tomorrow morning • Many thanks to Wick Haxton for giving us the extra time • 14C in deep oilfields • Homestake rails as a source of radiopure structural and shielding material

  2. 14C in deep oilfields (paper 5, to be submitted to NIM) • Paper by G.B., E. Carter (RET), N. Harris, V. Paolone • Borexino results and partial interpretation (Schoenert-Resconi) • Single carbon chemistry, gas field • Tests and further research (by others)

  3. 14C in petroleum • The original (atmospheric) 14C in petroleum is long gone • 14C recharged underground by neutron flux from rock • The Solar Neutrino TPC needs at least 14C/12C=r<10-18 to work in the (pp) region, Borexino/Kamland need r<10-21

  4. The Borexino result • Borexino, using the CTF facility, found (G. Alimonti et al., Phys. Lett. B 422, 349, 1998) r=(1.94+-0.09)10-18 for Lybian petroleum • However, a previous test on methane gave a limit of r< 10-18 • They have since measured petroleum from the Corpus Christi, TX, area at r=11X10-18 • Borexino and Kamland have overwhelming 14C backgrounds below 250 keV

  5. Interpretation (Schoenert-Resconi) • Identifies dominant reaction as 14N(n,p)14C • Petroleum has typical 2% nitrogen content due to biological origin (i.e, DNA) • Identifies the best oilfields as having low U/Th, low N • Predicts 10-16 <r< 10-20

  6. Nuclear reactions

  7. Our approach: focus on methane • Methane is easy to separate by boiloff • Methane has different chemistry than other hydrocarbons • Isotopical separation does not work unfortunately • Chain must proceed as:

  8. Single C reaction products in CH4

  9. Methane yield by hydrocarbon

  10. Consider a simple model for 14C(predicts 10-17 >r>10-22)

  11. Some facts about gasfields • Petroleum starts as crude and becomes a gas as it ages (hotter, deeper) • Light alkanes migrate and move away – gasfields with zero nitrogen can be found • Natural gas is typically 90% methane, with some ethane and propane

  12. Specifying the perfect gasfield • 90% methane, with some ethane (factor 50 purity) • proven low U content (several) (factor 30) • No kerogen, no nitrogen (factor 50) (some) • No bacterial activity • No H2S • Probably no water is better • Double boiloff recommended (CO)

  13. Conclusions • Two new ways to strongly suppress 14C in hydrocarbons – both use methane as feedstock • TPC almost certainly immune to 14C backgrounds • Our colleagues have work to do, including devising a clean industrial reducing process, but r=10-22 appears feasible

  14. Homestake rails as a source of radiopure structural and shielding material (Paper 7) • Paper by G. Aberle, G. B., R. Brodzinski, E. Loh • Major steel contaminants • Quantity and quality

  15. Steel major radiocontaminants • 54Mn (half life=312 days, E=835 keV). Activated by cosmic rays at surface, equilibrium activity 5mBq/Kg (equivalent U=10-10g/g) • 60Co (half life=5.27 days, E=1.2 MeV). Also cosmic-activated, but mostly due to contamination. Usually dominant radiocontaminant, wide variance. • U limits at the 10-11g/g level exist for some steels. Some variance expected once measurements are refined

  16. Homestake steel (older than 50 years) • Free of both 54Mn and 60Co ( 60Co measured by R.B. on 125 yrs old steel) • 75 miles of rails older than 50 years can be readily harvested (5 kTons) • 1 kTon available in I-beams and pipes of various sizes • Many advantages (spikes, no travel, standard sizes, several sizes, records, upper levels, very cheap)

  17. Goals and possible uses • 10-11-10-13g/g U/Th may be feasible (need measurements) • To be used as part of the neutron shield for DRIFT (G.B.) • If 10-11g/g, Solar Neutrino TPC detector plane frames (G.B.) • If 10-12g/g, Solar Neutrino TPC inner shield support (deionized ice) (G.B.)

  18. Conclusions • Homestake rails are potentially a great treasure which could serve the need for radiopure structural and/or solid shielding material of EVERY NESS02 PARTICIPANT • The funding agencies should consider funding preliminary testing of the hypothesis

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