In reply to Alain Sepeda's message of Tue, 14 Oct 2014 08:53:26 +0200: Hi, [snip] >I think we can eliminate 2 kind of impossible reaction : >- those involving free neutrons that would be thermalized even rarely, and >detected
The reactions described below do not involve free neutrons. A bound neutron migrates directly from one nucleus to another. This is a classic quantum tunneling reaction. >- those not geometrically balanced which would creat a gamma tha would be >detected. The initial energy of the reaction appears as kinetic energy of the daughter nuclei, both of which are created in their ground state because only a single nucleon transfers (this is a guess). Both new nuclei are stable. Hence no gammas. The new nuclei are "heavy", and thus "slow", so no bremsstrahlung to speak of is created. K shell electron displacement will only result in low energy X-rays, 7.5 keV for Ni, in the Ni-Li reaction, 1.2 keV for Mg in the Mg reaction. These are readily absorbed by the encasement. The first excited state of Mg26 is at 1.8 MeV. That of Mg24 is at 1.3 MeV. In the Mg25 reaction, both the new nuclei have about 1.9 MeV. Secondary radiation will be very low intensity because the high central charge on both nuclei (12) and the low velocity will mean that the first excited state of either Mg24 or Mg26 will only be activated on very rare occasions indeed. This is about as clean a nuclear reaction as you are going to find...and just the Magnesium in the top 1 km of the Earth's crust would supply all our energy needs at the current rate of use for 20 billion years (if I got my sums right). (Furthermore, there is a lot of Magnesium is sea water, which can be readily extracted with ion-exchange technology, ensuring that the landscape need not be disturbed by mining). > >geometry is the key because of CoM. >probably the electron is too, but that is not sure... > >2014-10-14 7:22 GMT+02:00 <[email protected]>: > >> Hi, >> >> (This email best viewed with a fixed width font). >> >> Prime candidates are even numbered elements with an odd number of >> neutrons. This >> is because subtracting or adding a neutron produces an even-even nucleus, >> and >> these tend to be stable. >> >> The reactions that yield the most energy would use a neutron source where >> the >> neutron is only bound loosely. Here is a table with some isotopes and the >> binding energy of the odd neutron (the lower the binding energy, the >> easier it >> is to remove):- >> >> Isotope Energy (MeV) ppm of the element in the Earth's crust >> D 2.2 ! >> Li7 7.25 13 ! >> Be9 1.573 1.5 >> C13 4.946 200 >> Mg25 7.331 32000 ! >> Si29 8.474 267700 ! >> Ca43 7.933 52900 ! >> Ti47 8.88 5400 ! >> Ti49 8.142 " ! >> Ge73 6.783 1.6 >> Se77 7.419 0.05 >> Sr87 8.428 260 >> Zr91 7.194 100 >> Mo95 7.369 1 >> Mo97 6.821 " >> Pd105 7.094 0.001 >> Cd111 6.976 0.098 >> Sn117 6.943 2.5 >> Sn119 6.483 " >> Ba135 6.973 250 >> Ba137 6.90 " >> >> The most useful isotopes are likely to be those of low atomic number, high >> abundance, and reasonably large isotopic percentage of the element in >> question. >> >> These have been indicated with an "!". >> >> In particular, Mg25 may be an opportunity that has been missed so far. It >> is >> interesting both because of it's abundance, and because of the neutron >> binding >> energy comparable to that of Lithium. >> >> Possible interesting reaction:- >> >> 25Mg + 25Mg => 26Mg + 24Mg + 3.763 MeV >> >> Furthermore the energy is divided over two nuclei of almost equal mass, >> hence >> each gets about half (1.9 MeV), so this could be a very clean reaction. >> >> >> Regards, >> >> Robin van Spaandonk >> >> http://rvanspaa.freehostia.com/project.html >> >> Regards, Robin van Spaandonk http://rvanspaa.freehostia.com/project.html
