No abstract

No abstract

A (11)C molecular production/separation system (CMPS) has been developed as part of an isotope separation on line system for simultaneous positron emission tomography imaging and heavy-ion cancer therapy using radioactive (11)C ion beams. In the ISOL system, (11)CH4 molecules will be produced by proton irradiation and separated from residual air impurities and impurities produced during the irradiation. The CMPS includes two cryogenic traps to separate specific molecules selectively from impurities by using vapor pressure differences among the molecular species. To investigate the fundamental performance of the CMPS, we performed separation experiments with non-radioactive (12)CH4 gases, which can simulate the chemical characteristics of (11)CH4 gases. We investigated the separation of CH4 molecules from impurities, which will be present as residual gases and are expected to be difficult to separate because the vapor pressure of air molecules is close to that of CH4. We determined the collection/separation efficiencies of the CMPS for various amounts of air impurities and found desirable operating conditions for the CMPS to be used as a molecular separation device in our ISOL system.

Electron beam ion sources (EBISs) provide the highest charge states of ion produced, high pulse ion currents, and a good emittance of an ion beam but an average ion current usually less than that for other sources of highly charged ions, for example, electron cyclotron resonance. The reason for that is an unusually small volume of electron–ion interaction, which is limited by the acceptable length of the source and by the electron beam perveance. To overcome the last limit while conserving all the advantages of the EBIS mentioned, the general idea of a tubular electron beam ion source (TEBIS) with an off-axis ion extraction is proposed. Construction of a TEBIS and its use in the normal or in the reflex mode of operation could increase an EBIS ion output 100–1000 times. The configuration of TEBIS and the current status of its development is described.

The Electron String type of Ion Sources (ESIS) was developed, constructed and tested first in the Joint Institute for NuclearResearch. 1 These ion sources can be the appropriate sources for production of pulsed C 4+ and C 6+ ion beams which can be used for cancer therapy accelerators. In fact the test ESIS Krion-6T already now at the solenoid magnetic field only 4.6 T provides more than 10 10 C 4+ ions per pulse and about 5·10 9 C 6+ ions per pulse. Such ion sources could be suitable for application at synchrotrons. It was also found, that Krion-6T can provide more than 10 11 C 6+ ions per second at 100 Hz repetition rate, and the repetition rate can be increased at the same or larger ion output per second. This makes ESIS applicable at cyclotrons as well. As for production of 11 C radioactive ion beams ESIS can be the most economic kind of ion source. To proof that the special cryogenic cell for pulse injection of gaseous species into electron string was successfully tested using the ESIS Krion-2M. 2