Patent Number: 048184683
Section: claims

1. A process for preparing .sup.123 I which comprises: irradiating with a proton beam in an irradiation zone a liquid sample of XI as a target material, wherein X is alkali metal or I, the protons in said beam having an energy in the range of 60-70 MeV at a power level of at least about 5 .mu.a, wherein the thickness of the XI sample is sufficient to reduce the energy of said particles by from about 15-25 MeV and said beam irradiating a substantial portion of said liquid sample in said zone;  continuously passing a stream of helium onto the surface of said liquid sample in said irradiation zone whereby .sup.123 Xe produced by said irradiation is entrained with said helium and carried from the irradiation zone to a condensing zone;  cooling said helium stream in said condensing zone returning XI to said irradiation zone and transferring said helium stream to a collection zone;  condensing .sup.123 Xe by cooling said helium stream in said collection zone to a temperature below the condensation temperature of .sup.123 Xe, and collecting .sup.123 Xe in said collection zone; and  allowing .sup.123 Xe to decay to .sup.123 I.  irradiating with a scanning proton beam in an irradiation zone a liquid sample of XI as a target material, wherein X is sodium or I, the protons in said beam having an energy in the range of 60-70 MeV at a power level of from about 10 .mu.a to 20 .mu.a, wherein the thickness of the XI sample is sufficient to reduce the energy of said particles by from about 15-25 MeV, while maintaining the temperature at or about the melting point of XI, but not to exceed 100.degree. C. above the melting point of XI and said beam irradiating a substantial portion of said liquid sample in said zone;  continuously passing onto the surface of said target material in said irradiation zone a helium stream containing up to 0.2 volume percent xenon, whereby .sup.123 Xe produced by said irradiation is entrained with said helium and carried from said irradiation zone to a condensing zone;  cooling said helium stream in said condensing zone and returning condensed XI to said irradiation zone;  removing any entrained I.sub.2 from said helium stream exiting from said condensing zone and transferring the substantially I.sub.2 free helium stream to a collection zone;  condensing .sup.123 Xe by cooling said helium stream in said collection zone to a temperature below the condensation temperature of .sup.123 Xe and collecting .sup.123 Xe in said collection zone; and  transferring said condensed .sup.123 Xe in vacuo by evaporation and condensation from said collection zone to a decay zone where .sup.123 Xe decays to .sup.123 I to provide high purity .sup.123 I. 2. A method according to claim 1, wherein said condensed .sup.123 Xe is transferred in vacuo by evaporation and condensation to a second vessel at a pressure below about 50.mu. mercury to enhance the purity of the .sup.123 I obtained from decay of .sup.123 Xe. 3. A method according to claim 1, wherein said helium stream has from about 0-0.2 volume percent xenon and entrained I.sub.2 is removed from said helium stream exiting from said condensing zone. 4. A method according to claim 1, wherein XI is sodium iodide and the temperature of said target material is in the range of about 650.degree.-720.degree. C. 5. A method according to claim 1, wherein XI is I.sub.2 and the temperature of said target material is in the range of about 100.degree.-130.degree. C. 6. A method according to claim 1, wherein said helium stream is passed through said target material at a rate of about 10-60 ml per minute. 7. A method according to claim 1, wherein said helium stream is heated by said liquid sample prior to passing onto the surface of said liquid sample. 8. A method according to claim 1, wherein XI is placed in tandem in a second target zone behind said target zone having a thickness sufficient to reduce the energy of the protons' radiation exiting from said first zone by 15-20 MeV; and isolating .sup.125 Xe produced by said radiation exiting from said first zone. 9. A method for preparing .sup.123 I which comprises: 10. A method according to claim 9, where XI is NaI. 11. A method according to claim 9, where XI is I.sub.2. 12. A method according to claim 9, wherein said helium stream is heated by said target material prior to passing onto the surface of said target material.