Citat:
Ursprungligen postat av bjornebarn
Nej, för att alfapartikel-bombardering skall kunna transmutera aluminium (Al-27 för att vara specifik) måste partiklarna accelereras i en partikelaccelerator, ty annars överkommer de inte den repulsiva elektromagnetiska kraften. Man behöver alltså inte bry sig det minsta om huruvida man har aluminiumföremål i närheten eller ej.
Att läsa om historiska experiment kan vara lärorikt.
Experiment utförda utan partikelaccelerator med alfapartiklar direkt från ett radioaktivt ämne.
Citat:
http://books.google.se/books?id=YpEiPPFlNAAC&printsec=frontcover&hl=sv
sid 95-96
Radioactivity/Introduction And History Michael F. L'Annunziata
They irradiated aluminum foil with alpha particles from a polonium source. The energy of the alpha particles colliding with the aluminum could be controlled by placing the polonium at various distances from the aluminum. The irradiation of aluminum foil by the polonium alpha particles produced neutrons and positrons. When the polonium source was moved away from the aluminum to a distance beyond the reach of the alpha particles (the alpha particles from polonium-216 have an energy of 6.78 MeV and these cannot travel beyond 5.3 cm as calculated according to eq(1.9) of Chapter 1), the neutron emission from the alpha-irradiated aluminum would cease; however, to their amazement, the Joliot-Curies discovered that the positron emission would continue. They measured the positron emission with a Geiger counter and found that the number of positrons emitted would diminish with time with an average lifetime of less than 5 min. The interaction of the alpha particles with the aluminum foil produced a new radioactive isotope, yet unknown to mankind.
The Joliot-Curies were able to demonstrate that the new isotope was radioactive phosporus using the following test an reasoning:
. . .
Aluminium27 + alfapartikel => Fosfor30 + neutron
sid 95-96
Radioactivity/Introduction And History Michael F. L'Annunziata
They irradiated aluminum foil with alpha particles from a polonium source. The energy of the alpha particles colliding with the aluminum could be controlled by placing the polonium at various distances from the aluminum. The irradiation of aluminum foil by the polonium alpha particles produced neutrons and positrons. When the polonium source was moved away from the aluminum to a distance beyond the reach of the alpha particles (the alpha particles from polonium-216 have an energy of 6.78 MeV and these cannot travel beyond 5.3 cm as calculated according to eq(1.9) of Chapter 1), the neutron emission from the alpha-irradiated aluminum would cease; however, to their amazement, the Joliot-Curies discovered that the positron emission would continue. They measured the positron emission with a Geiger counter and found that the number of positrons emitted would diminish with time with an average lifetime of less than 5 min. The interaction of the alpha particles with the aluminum foil produced a new radioactive isotope, yet unknown to mankind.
The Joliot-Curies were able to demonstrate that the new isotope was radioactive phosporus using the following test an reasoning:
. . .
Aluminium27 + alfapartikel => Fosfor30 + neutron
Fosfor30 är inte är stabil utan sönderfaller vidare till kisel30 under utsändande av en positron. Halveringstid 2.6 minuter.
Mina egna test av Americium241 och aluminium ger istortsett samma resultat. Att det knastrar och sprakar utav bara helvete i ett par minuter efter att strålkällan avlägsnats från aluminiumet. Dvs att det bildats ett radioaktivt grundämne som sänder ut starkt joniserande strålning.
(Men det kan ju förstås vara föroreningar i aluminiumet bestånde av magnesium eller aluminum26 som reagerar med alfastrålningen ?)
Citat:
Most americium is produced by bombarding uranium or plutonium with neutrons in nuclear reactors – one tonne of spent nuclear fuel contains about 100 grams of americium.
Americium-241 is the most prevalent isotope of americium in nuclear waste. It is the americium isotope used in an americium smoke detector based an ionization chamber.
Americium-241 decays to 237Np emitting alpha particles of 5 different energies, mostly at 5.486 MeV (85.2%) and 5.443 MeV (12.8%). Because many of the resulting states are metastable, they also emit gamma rays with the discrete energies between 26.3 and 158.5 keV.
Americium-241 is the most prevalent isotope of americium in nuclear waste. It is the americium isotope used in an americium smoke detector based an ionization chamber.
Americium-241 decays to 237Np emitting alpha particles of 5 different energies, mostly at 5.486 MeV (85.2%) and 5.443 MeV (12.8%). Because many of the resulting states are metastable, they also emit gamma rays with the discrete energies between 26.3 and 158.5 keV.
- - -
Edit:
Positroner som är antimateria förintas rätt så snabbt under utsändandet av gamma.
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Senast redigerad av WriteMasterTM 2012-07-27 kl. 23:25.
Senast redigerad av WriteMasterTM 2012-07-27 kl. 23:25.
