摘要:

A brief review of the current status of Accelerator Mass Spectrometry is presented, with emphasis on some of the most recent technical developments. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.58960

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

The National Ocean Sciences Accelerator Mass Spectrometry Facility (NOSAMS) has completed the carbon isotope analysis of a major fraction of the 13,500 sea water samples collected in the framework of the World Ocean Circulation Experiment (WOCE) from three of the major world oceans between 1991 and 1996. We will describe the AMS technique employed at NOSAMS and, using 3-D data visualization techniques we will demonstrate the present status of the data set and offer some preliminary conclusions about the distribution of natural and anthropogenic14Cin the oceans. In particular, we will be able to compare some of the data with results from the Geochemical Ocean Sections Study (GEOSECS, 1972–1978) to obtain information about the time dependence of oceanic circulation processes, tracing the14Csignal introduced into the oceans during the atmospheric nuclear bomb tests in the 1950’s and 1960’s. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.58989

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

The compact, high current, 2.45 GHz microwave-driven plasma ion source which was built for the Chalk River TASCC facility is presently being adapted for testing as a gas ion source for accelerator mass spectrometry, at the Woods Hole Oceanographic Institution accelerator mass spectrometer. The special requirements for producing carbon-ion beams from micromole quantities of carbon dioxide produced from environmental samples will be discussed. These samples will be introduced into the ion source by means of argon carrier gas and a silicon capillary injection system. Following the extraction of positive ions from the source, negative ion formation in a charge exchange vapor will effectively remove the argon from the carbon beam. Simultaneous injection of the three carbon isotopes into the accelerator is planned. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.58990

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

Neutral Injection was first used forty years ago for the acceleration of He ions by tandem accelerators, before the advent of the negative He ion source. Later, almost universal sputter-negative-ion sources were developed and the use of neutral injection fell into disuse for nuclear physics with tandem accelerators. With the advent of Accelerator Mass Spectrometry (AMS) in 1977 the idea of neutral injection was revived briefly. Now that AMS has matured and Radioactive Ion Beam (RIB) acceleration is being undertaken for nuclear physics, we propose the revival of a modern form of Neutral Injection. The use of resonant electron transfer for neutralization is discussed, as is the scattering degradation of the ion beam during neutralization and re-ionization. We show that the process is suitable for some types of AMS and the acceleration for RIB of positive ions, that form negative ions with difficulty, to a few MeV. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.58962

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

Construction has begun on ISAC, a radioactive ion beam (RIB) and accelerator facility that utilizes the ISOL (on-line isotope separation) production method. A five-year budget for this new radioactive beam facility at TRIUMF was approved in June 1995. ISAC includes: a new building with 5000 m2of floor space, a beam line with adequate shielding to transport up to 100 &mgr;A of 500 MeV protons from the TRIUMF cyclotron to two target/ion-source stations, remote handling facilities for the targets, a high-resolution mass-separator, linear accelerators and experimental facilities. The ISAC target/ion source station permits the production of nuclei far from stability over a large isotopic range with high luminosity. Ions from the target/ion-source will be transported at energies up to 60 keV through a low-resolution pre-separator magnet followed by a high-acceptance, high-resolution mass-separator magnet to a variety of low energy experimental stations. Alternatively, ions withq/A⩾1/30and an energy of 2 keV/amu can be bunched in the low energy beam transport line prior to a RFQ accelerator. The final energy will be variable from 0.15 to 1.5 MeV/amu. The accelerated beams will be used primarily for nuclear astrophysics studies. The buildings are now complete and the commissioning of the target/ion source, mass separator and RFQ systems has started. The TRIUMF neutral atom trap (TRINAT) is scheduled to begin using the low energy ISAC beam in November 1998. The full energy beam will become available for the DRAGON recoil spectrometer at the end of 2000. A new five-year plan will be presented to the Canadian Government before the end of 1998. The plan includes an upgrade of ISAC to permit acceleration of the RIB up to 6.5 MeV/amu for masses up to 150. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.58963

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

An ISOL-based radioactive nuclear beam facility at KEK-Tanashi has been constructed. The linac complex to accelerate radioactive beams comprises a 25.5 MHz split coaxial RFQ (SCRFQ) and a 51 MHz interdigital-H (IH) linac, and accelerates heavy ions up to 1 MeV/u. Beam tests using stable nuclear beam have been done in order to examine the performance of the linacs. Acceleration tests of a radioactive nuclear beam was also performed. This facility is a prototype for the exotic nuclei arena (E-arena) of the proposed Japanese Hadron Facility (JHF), in which 3 GeV, 10 &mgr;A protons is used as a primary beam, and a radioactive nuclear beam is accelerated up 6.5 MeV/u by an extension of the IH linac. In this paper, outline, present status and future plan of the facility are reported with emphasis on the heavy ion linacs. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.58964

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

The U.S. Nuclear Science Community in its 1996 Long Range Plan identified an advanced radioactive ion beam (RIB) facility based on the ISOL technique as the next major facility to be constructed for U.S. nuclear physics. The proposed Spallation Neutron Source (SNS) for Oak Ridge National Laboratory, whose construction design funds have recently been appropriated, offers a unique opportunity for the construction of this new facility. Plans for extracting a proton beam from the SNS, transporting it to the RIB facility, and constructing the new RIB facility at the SNS site are discussed, as are the ISOL targets, radiation handling, isobaric separation, acceleration of beams of radioactive ions, and the layout of the experimental areas. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.58965

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

The Argonne concept for an accelerator complex for efficiently producing high-quality radioactive beams from ion source energy up to 6–15 MeV/u is described. The Isotope-Separator-On-Line (ISOL) method is used. A high-power driver accelerator produces radionuclides in a target that is closely coupled to an ion source and mass separator. By using a driver accelerator which can deliver a variety of beams and energies the radionuclide production mechanisms can be chosen to optimize yields for the species of interest. To effectively utilize the high beam power of the driver two-step target/ion source geometries are proposed: (1) Neutron production with intermediate energy deuterons on a primary target to produce neutron-rich fission products in a secondary238Utarget, and (2) Fragmentation of neutron-rich heavy ion beams such as18Oin a target/catcher geometry. Heavy ion beams with total energies in the 1–10 GeV range are also available for radionuclide production via high-energy spallation reactions. At the present time R&D is in progress to develop superconducting resonator structures for a driver linac to cover the energy range up to 100 MeV per nucleon for heavy ions and 200 MeV for protons. The post accelerator scheme is based on using existing ISOL-type 1+ ion source technology followed by CW Radio Frequency Quadrupole (RFQ) accelerators and superconducting linacs including the present ATLAS accelerator. A full-scale prototype of the first-stage RFQ has been successfully tested with RF at full design voltage and tests with ion beams are in progress. A benchmark beam,132Sn &at; 7&hthinsp;MeV/u,requires two stripping stages, one a gas stripper at very low velocity after the first RFQ section, and one a foil stripper at higher velocity after a superconducting-linac injector. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.58991

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

A description is given of the radioactive ion beam facility, SIRIUS, proposed to be built at ISIS, the world leading pulsed neutron source. Up to 100 &mgr;A of 800 MeV protons from the ISIS synchrotron will be taken down a new beam line into a target station complex where radioactive nuclei will be formed as a result of the interaction with the target. The nuclei are subsequently ionised and accelerated to 200 kV. The beam passes through a broad range spectrometer to provide several beams of different ion species simultaneously. One beam passes through a high resolution spectrometer and is accelerated in an RFQ and a superconducting linear accelerator to 10 MeV/amu, for nuclear physics research. The other beams are taken to a low energy experimental area. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.58992

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

Issues are discussed in producing intense Radioactive Ion Beams (RIB) using the Isotope Separator On-Line (ISOL) approach, based on the use of thick targets employed at existing facilities. Some new physics studies may possibly be addressed by improving the performance of these existing targets through improvements in release and effusion properties to optimize the RIB yields. It is, however, acknowledged that many desired physics objectives using RIB can be met only by employing production beams of energetic light ions or protons with currents up to 100 &mgr;A. Development of targets that use such intense production beams needs to address the requirement to control operational temperatures derived from internal production beam interactions with the target materials. In addition, issues arise for target materials in terms of their thermal characteristics, such as thermal conductivity and thermo-mechanical properties. A target concept is described for an in-beam test of a prototype target for actual thermal behavior under RIB production conditions. For such a test, a high-power test facility is needed; fortunately, the prototypical production beam currents required exist at the TRIUMF accelerator facility. An experimental proposal has been approved for such a test. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.58967

出版商:AIP    

年代:1999

数据来源: AIP