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. 14 C in petroleum The original (atmospheric) 14 C in petroleum is long gone 14 C 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 14 N(n,p) 14 C 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 Reaction  mbarn) Comment 17 O(n,  ) 14 C 235 14 N(n,p) 14 C1830 13 C(n,  ) 14 C 1.4 11 B( ,n) 14 C 20-2002-5 MeV energy 226 Ra => 14 C-tripartition

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 CH 4 ImpuritiesNone2% O 2 1.2% C 2 H 4 CO <0.226.8<0.2 CH 4 13.9<0.15<0.2 C2H2C2H2 17.732.325.2 C2H4C2H4 12.430.523.5 C2H6C2H6 23.9<0.53.4 C3H8C3H8 11.10.21.7 Higher20.91646.2

9. Methane yield by hydrocarbon HydrocarbonMethane yield (%) CH 4 13.9 C2H6C2H6 2.1 C3H8C3H8 2.9 cyclohexane6.7 N-hexane5.6

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 H 2 S 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 -10 g/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 -11 g/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 -13 g/g U/Th may be feasible (need measurements) To be used as part of the neutron shield for DRIFT (G.B.) If 10 -11 g/g, Solar Neutrino TPC detector plane frames (G.B.) If 10 -12 g/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