- Email: [email protected]
Status and plans for the PRIME Lab AMS facility
Nuclear Instruments
and Methods in Physics Research B 123 (1997) 69-72
Beam Interactions with Materials 8 Atoms
ELSEVIER
Status and plans for the PRIME Lab AMS facility D. Elmore a,* , X. Ma a, T. Miller a, K. Mueller a, M. Perry a, F. Rickey a, P. Sharma ‘, P. Simms a, M. Lipschutz b, S. Vogt b a Department of Physics. ofChemistry.
b Department
Purdue
University.
Purdue
Unioersity.
Wesr Lajbyette. West Lajtiyette.
IN 47907, IN 47907.
USA USA
Abstract The operation, status, performance, and upgrade plans for the Purdue Rare Isotope Measurement Laboratory (PRIME Lab) are described. The AMS system is in routine operation for all of the commonly-used AMS nuclides. Chemical preparation is being performed for all nuclides measured in many different matrices. Construction of a new injector and terminal stripper system is in progress; a fast-isotope-switching system is in the final design stage.
1. Introduction The Purdue Rare Isotope Measurement Laboratory is the National Science Foundation facility for measurement of the nuclides “Be, 26A1, 36C1, 4’Ca and ‘291. 14C is also measured, but at low priority since the NSF supports two other facilities to measure this nuclide. PRIME Lab was established by Purdue University in February 1989 and first funded by the NSF in April 1990. The first AMS measurement took place in December 1990, and automated slow-isotope-cycling started in November 1991. An upgrade of the tandem (new accelerator tubes and charging system) was completed in May 1994. AMS measurements now run unattended for 6-10 h periods. We have chemically prepared 260 samples and measured 1619 AMS samples in the past year.
2. AMS system The AMS system (Fig. 1) is based on an upgraded FN (8 MV) tandem accelerator. The ion source is a sphericalionizer cesium-sputter source (Southern Cross model K-60) with a custom 8-sample wheel. Isotope ratios are obtained by cycling the injector and analyzer magnets [I]. A 20” electrostatic analyzer removes particles of different energy that pass the magnetic analyzers. The multi-plate gas ionization detector and data acquisition system have special features for separation of 36C1 and 36S [2].
* Corresponding author. Fax: [email protected]. 0168-583X/97/$17.00 PII
+ l-317-494-0706;
email:
As we approach 2000 AMS measurements per year, it becomes increasingly important to automate the measurement process to reduce operating costs and to improve consistency in measurements. In the past year we have placed an &sample wheel under computer control. In addition, unattended operation required programming an expert system that responds to the occasional abnormal events such as 36C1 samples with high 36S interference, system parameters outside of acceptable range, and unsteady beam. Some problems, such as skipping a bad sample, can be handled by the computer. For others, such as no beam current, the program will select a blank (to save the unknown sample material) and call an operator. The data reduction of AMS results is also completely automated. Final isotope ratios (background subtracted with propagated uncertainties) are displayed as the samples are measured [3], along with any previous results (since 1993). Sample results are also available immediately to users on the World Wide Web. The existing on-line sample database is being upgraded to Oracle. Quality assurance and quality control procedures are being implemented
el-
[41. PRIME Lab AMS performance data are given in Table 1. To generate data for columns on source current, transmission, and blank value, data for all samples in a recent run were histogrammed and the 10% and 90% integration points were recorded. The low values of the source currents generally correspond to small samples. High values of the blank result from cross contamination while measuring high-level unknowns at the end of a run; the ion source is cleaned before low-level samples are measured. AMS of all nuclides listed in the introduction has been demonstrated with the exception of 4’Ca; work on 4’Ca detection
0 1997 Elsevier Science B.V. All rights reserved
SOl68-583X(96)00621-0
III. EXISTING FACILITIES
D. EImore et al./Nucl.
70
Insb. and Meth. in Phys. Res. B 123 (1997) 69-72
Accelerator \
Analyzing Magnets
Electrostatic Analyzer Injector Magnet Detector Fig. I, The AMS system at PRIME Lab, based on an 8 MV tandem accelerator (model FN). using CaH, and CaF, is in progress. We have demonstrated 1% precision for ‘“C/ 13C ratios; we are developing capability for this nuclide primarily for local projects and for projects that involve measurement of other AMS nuclides at PRIME Lab. Precision for other nuclides is usually limited by counting statistics to somewhat larger than 1%; typical uncertainties for 36Cl/ 35Cl ratios (for values of 36Cl/Cl above 10-13) is 3%. ‘*‘I is measured without an injector electrostatic analyzer and without a time-of-flight detector, with aluminum sample holders, there is no evidence of ‘*‘Te and ‘*‘I interference at the 20 X IO-l5 level [5]. For measurements of 36CI in rocks, the chloride content of the rock needs to be determined. For chloride contents below about 50 ppm, other methods such as ion selective electrode (ISE) become difficult and precision is not adequate. Therefore, we have developed an isotope dilution technique using a 35Cl spike as a carrier material The 37Cl/35Cl ratio is measured in the injector Faraday cup before and after the 36CI/ 35Cl ratio is measured by AMS. This measurement is automated and adds only a few minutes to AMS of the sample, and no additional chemistry or sample handling is required. Precision is 3% or better down to a few ppm. Good precision is not needed
for lower concentrations since 36Cl production is usually then dominated by spallation of Ca and K. The system has been tested by measuring by both ISE and ID/MS on numerous unknown samples and several USGS standards. Agreement has been good except for two of the USGS standards; reasons for the discrepancies are under investigation.
3. Upgrade plans
The first phase of our upgrade program has been completed. The major components of this phase were the installation of an NEC Pelletron charging system, shielded column grading resistors, and spirally-inclined titaniumelectrode acceleration tubes. This provides a much more stable accelerator terminal voltage than was provided by the belt charging system. The new acceleration tubes provide a much lower loss in the transmitted beam largely because of an optical error in the design of the original tubes. Based on experience gained from the sparks caused
Table 1 Performance data for the PRIME Lab AMS system a)
“Be 14C 26AI =c1
Charge state
Stripper ‘)
Terminal voltage (MV)
Source current b, (FA)
Transmission b.d) (%I
Blank b, (lo- ‘5)
Samples measured per year ‘)
3+ 4+ 3+ 7f
G G F
6 4 7
G
3
17/20 30/35 14/21 15/21 1.7/2.1
2.3/44
5+
2/5 15/52 0.07/0.32 4/11 ‘/g
155 20 427 913 104
129
I
at Based on research unknowns (blank levels include chemistry blanks). b, Values are 10%/90% distribution points based on all samples. ‘) G/F = gas/foil stripping. d, Percent of particles transmitted from injector to analyzer. ‘) Samples measured in the one year period May 1995 through April 1996.
1.6/7 4.5/30 1.2/19 20/195
D. Elmore et ul./Nucl.
Instr. and Meth. in Phys. Res. B I23 (1997169-72
by the faulty belts, filtering was added to signal and power lines entering the accelerator pressure vessel. Commercially available pi filters were used on all of the low voltage wiring entering the accelerator, and filters were constructed for all of the high voltage connections. Operational experience with the initial phase of the upgrade demonstrates great improvement in the useful operating voltage from 6 MV to 7 MV. In addition, the frequency of tank sparks was reduced by more than an order of magnitude. The beam transmission improved from 8% to 20% (for 36Cl) and the terminal ripple reduced by a factor of 5. The electrical filtering has resulted in no damage to the Pelletron power supplies (a fairly common problem) after sparks. In addition, there have been no other equipment failures that have been attributed to tank sparks. These and other improvements have resulted in a factor of two improvement of the AMS precision for 36C1 measurements and a factor of 3 to 5 improvement in sample measuring capacity. The next phase of the upgrade [6] is currently underway. This phase will include rebuilding the beam line between the source and the injector magnet, rebuilding the stripper assembly in the accelerator terminal, and the integration of the controls for this equipment into the VISTA control system which will ultimately control the entire accelerator. Most of the components for the ion source beam line have already been purchased, and custom components are under construction. Most of the drawings for the terminal components are completed. A large pressure test vessel (a used small accelerator tank) is currently being installed. The entire terminal stripper assembly will fit in this test fixture to permit pressure testing and leak checking before the accelerator is shut down for this part of the upgrade. Several critical components for the terminal, such as one of the turbo pumps, are ready for pressure testing. The upgrade of the terminal will include the installation of a fiber-optic communication system to permit computer control of the new terminal components. These improvements are expected to make a substantial improvement in the beam transmission and reduction of interferences for AMS measurements. Initial planning is underway for the installation of the new AMS injector. Only minor changes have been made to the design presented at AMS-6 [6]. This design will provide for the ability to do fast switching once the positive ion analysis portion of the accelerator is also upgraded. The computer control system will be integrated into the accelerator systems during the upgrade to eliminate the need for the construction of manual controls.
71
sample preparation laboratories [8] is complete and preparation techniques for the nuclides listed have been developed for a wide variety of matrices including 36Cl and ‘291 in water, 26Al and “Be in quartz, “Be in soils, and 36C1 in various rock mineral fractions. PRIME Lab chemistry operations are now carried out mainly in two refurbished laboratories in the Department of Chemistry. The design of these labs was based upon ideas used in NASA’s lunar processing laboratory in Houston where one of us (MEL) oversaw construction in l9771979. They were completed in 1995, have airborne particulate counts one-hundredth those of “normal” new chemistry laboratories and are completely equipped for routine processing of low-level samples. These laboratories are completely acid-resistant and, after a year‘s operations, exhibit no evidence for rust anywhere. The larger of the two laboratories, which ultimately will house a class-100 clean room, is chlorine-free and is used for 36Cl preparations. Other radionuclides are processed in the second laboratory. A prototype radiocarbon line has been constructed in the accelerator building and is in operation. Renovation of dual-purpose chemistry laboratories on another floor in the Department of Chemistry is currently under way and should be completed this year. Such laboratories have been and will be used for RNAA (radiochemical neutron activation analysis) studies of extraterrestrial materials, and for radiotracer chemistry associated with biomedical AMS measurements. PRIME Lab’s Chemistry Operations has received 1250 individual samples for single or multiple AMS target preparation during the past three years. From these, 1700 AMS targets were chemically and physically prepared: if we include target preparation for chloride determinations by ID-MS/AMS, the total number of targets increases to almost 1900 targets. About half of the AMS targets have been prepared for analysis of “Cl, while targets for 26Al and “Be analysis amount to 25% and 15%. The remainder includes samples for ‘29I and “‘Ca determinations analytical methods for which are being developed. Water and rock samples are the major matrices analyzed at PRIME Lab‘s Chemistry Operations, comprising about 60% and 25% of the sample volume. Developmental work at PRIME Lab’s Chemistry Operations has focused on: (a) physical and chemical sample preparation of rocks; (b) procedures for separating ““I from diverse matrices; (cl procedures for calcium hydride preparation and storage; and (d) procedures for 14C sample preparation. Activities include isolation and cleaning of mineral separates from rock matrices for “Cl analysis and pretreatment for a variety of materials for 14C analysis, including graphitization.
4. Chemical sample preparation PRIME Lab chemistry operations offers a physical and chemical sample preparation service for the local and international AMS community. Construction of two new
5. Research
program
There are over I25 users of our facility involved in 20 internal and 160 external projects [g]. Purdue-based goals
111.EXISTING FACILITIES
72
D. Elmore et al./Nucl.
Instr. ad Meth. in Phys. Res. B 123 (1997) 69-72
in earth and planetary sciences are to calibrate and develop for using cosmogenic radionuclides to study the history of rocks, soils, meteorites, and ground water through improvements in sample collection methods, chemical separation techniques, and theoretical models. Applications reported at this conference include glacial erosion of bedrock, the glacial history of Indiana, rock erosion rates, glacial, volcanic, and tectonic history of the Andes, Antarctic Meteorites, and the Mocs meteorite strewnfield. Purdue-based goals in the biomedical sciences are to develop methods for tracing aluminum, calcium and carboncontaining compounds in living systems; applications reported here include aluminum uptake in rats, aluminumcontaining adjuvants, and cholesterol. methods
References [l] M. Perry et al., these Proceedings Meth. B 123 (1997) 178.
CAMS-7), Nucl. Ins&. and
121D.L.
Knies and D. Elmore. Nucl. Instr. and Meth. B 92 (1994) 134. 131ES. Michlovich and D. Elmore, PRIME Lab Report PL9303 (Purdue University, West Lafayette, IN, 1993). 141D. Ehnore, L. Dep. R. Flack, M.J. Hawksworth, D.L. Knies, X.2. Ma, E.S. Michlovich, T.E. Miller, K.A. Mueller, F.A. Rickey. P. Sharma, P.C. Simms, H.-J. Woo, M.E. Lipschutz, S. Vogt, M.-S. Wang and MC. Monaghan, Nucl. Instr. and Meth. B 92 (1994) 65. El P. Shanna, D. Elmore, T. Miller and S. Vogt. these Proceedings CAMS-71, Nucl Instr. and Meth. B 123 (1997) 347. [61K.H. Purser, D. Elmore, K.A. Mueller, T.E. Miller, H.R. McK. Hyder and H. Enge, Nucl. Instr. and Meth. B 92 (1994) 69. Nucl. 171S. Vogt, M.-S. Wang, R. Li and M.E. Lipschutz, Instrand Meth. B 92 (1994) 153. b31P. Shanna, D. Elmore and S. Vogt, these Proceedings (AMS71, Nucl. Instr. and Meth. B 123 (1997) 199.
and Methods in Physics Research B 123 (1997) 69-72
Beam Interactions with Materials 8 Atoms
ELSEVIER
Status and plans for the PRIME Lab AMS facility D. Elmore a,* , X. Ma a, T. Miller a, K. Mueller a, M. Perry a, F. Rickey a, P. Sharma ‘, P. Simms a, M. Lipschutz b, S. Vogt b a Department of Physics. ofChemistry.
b Department
Purdue
University.
Purdue
Unioersity.
Wesr Lajbyette. West Lajtiyette.
IN 47907, IN 47907.
USA USA
Abstract The operation, status, performance, and upgrade plans for the Purdue Rare Isotope Measurement Laboratory (PRIME Lab) are described. The AMS system is in routine operation for all of the commonly-used AMS nuclides. Chemical preparation is being performed for all nuclides measured in many different matrices. Construction of a new injector and terminal stripper system is in progress; a fast-isotope-switching system is in the final design stage.
1. Introduction The Purdue Rare Isotope Measurement Laboratory is the National Science Foundation facility for measurement of the nuclides “Be, 26A1, 36C1, 4’Ca and ‘291. 14C is also measured, but at low priority since the NSF supports two other facilities to measure this nuclide. PRIME Lab was established by Purdue University in February 1989 and first funded by the NSF in April 1990. The first AMS measurement took place in December 1990, and automated slow-isotope-cycling started in November 1991. An upgrade of the tandem (new accelerator tubes and charging system) was completed in May 1994. AMS measurements now run unattended for 6-10 h periods. We have chemically prepared 260 samples and measured 1619 AMS samples in the past year.
2. AMS system The AMS system (Fig. 1) is based on an upgraded FN (8 MV) tandem accelerator. The ion source is a sphericalionizer cesium-sputter source (Southern Cross model K-60) with a custom 8-sample wheel. Isotope ratios are obtained by cycling the injector and analyzer magnets [I]. A 20” electrostatic analyzer removes particles of different energy that pass the magnetic analyzers. The multi-plate gas ionization detector and data acquisition system have special features for separation of 36C1 and 36S [2].
* Corresponding author. Fax: [email protected]. 0168-583X/97/$17.00 PII
+ l-317-494-0706;
email:
As we approach 2000 AMS measurements per year, it becomes increasingly important to automate the measurement process to reduce operating costs and to improve consistency in measurements. In the past year we have placed an &sample wheel under computer control. In addition, unattended operation required programming an expert system that responds to the occasional abnormal events such as 36C1 samples with high 36S interference, system parameters outside of acceptable range, and unsteady beam. Some problems, such as skipping a bad sample, can be handled by the computer. For others, such as no beam current, the program will select a blank (to save the unknown sample material) and call an operator. The data reduction of AMS results is also completely automated. Final isotope ratios (background subtracted with propagated uncertainties) are displayed as the samples are measured [3], along with any previous results (since 1993). Sample results are also available immediately to users on the World Wide Web. The existing on-line sample database is being upgraded to Oracle. Quality assurance and quality control procedures are being implemented
el-
[41. PRIME Lab AMS performance data are given in Table 1. To generate data for columns on source current, transmission, and blank value, data for all samples in a recent run were histogrammed and the 10% and 90% integration points were recorded. The low values of the source currents generally correspond to small samples. High values of the blank result from cross contamination while measuring high-level unknowns at the end of a run; the ion source is cleaned before low-level samples are measured. AMS of all nuclides listed in the introduction has been demonstrated with the exception of 4’Ca; work on 4’Ca detection
0 1997 Elsevier Science B.V. All rights reserved
SOl68-583X(96)00621-0
III. EXISTING FACILITIES
D. EImore et al./Nucl.
70
Insb. and Meth. in Phys. Res. B 123 (1997) 69-72
Accelerator \
Analyzing Magnets
Electrostatic Analyzer Injector Magnet Detector Fig. I, The AMS system at PRIME Lab, based on an 8 MV tandem accelerator (model FN). using CaH, and CaF, is in progress. We have demonstrated 1% precision for ‘“C/ 13C ratios; we are developing capability for this nuclide primarily for local projects and for projects that involve measurement of other AMS nuclides at PRIME Lab. Precision for other nuclides is usually limited by counting statistics to somewhat larger than 1%; typical uncertainties for 36Cl/ 35Cl ratios (for values of 36Cl/Cl above 10-13) is 3%. ‘*‘I is measured without an injector electrostatic analyzer and without a time-of-flight detector, with aluminum sample holders, there is no evidence of ‘*‘Te and ‘*‘I interference at the 20 X IO-l5 level [5]. For measurements of 36CI in rocks, the chloride content of the rock needs to be determined. For chloride contents below about 50 ppm, other methods such as ion selective electrode (ISE) become difficult and precision is not adequate. Therefore, we have developed an isotope dilution technique using a 35Cl spike as a carrier material The 37Cl/35Cl ratio is measured in the injector Faraday cup before and after the 36CI/ 35Cl ratio is measured by AMS. This measurement is automated and adds only a few minutes to AMS of the sample, and no additional chemistry or sample handling is required. Precision is 3% or better down to a few ppm. Good precision is not needed
for lower concentrations since 36Cl production is usually then dominated by spallation of Ca and K. The system has been tested by measuring by both ISE and ID/MS on numerous unknown samples and several USGS standards. Agreement has been good except for two of the USGS standards; reasons for the discrepancies are under investigation.
3. Upgrade plans
The first phase of our upgrade program has been completed. The major components of this phase were the installation of an NEC Pelletron charging system, shielded column grading resistors, and spirally-inclined titaniumelectrode acceleration tubes. This provides a much more stable accelerator terminal voltage than was provided by the belt charging system. The new acceleration tubes provide a much lower loss in the transmitted beam largely because of an optical error in the design of the original tubes. Based on experience gained from the sparks caused
Table 1 Performance data for the PRIME Lab AMS system a)
“Be 14C 26AI =c1
Charge state
Stripper ‘)
Terminal voltage (MV)
Source current b, (FA)
Transmission b.d) (%I
Blank b, (lo- ‘5)
Samples measured per year ‘)
3+ 4+ 3+ 7f
G G F
6 4 7
G
3
17/20 30/35 14/21 15/21 1.7/2.1
2.3/44
5+
2/5 15/52 0.07/0.32 4/11 ‘/g
155 20 427 913 104
129
I
at Based on research unknowns (blank levels include chemistry blanks). b, Values are 10%/90% distribution points based on all samples. ‘) G/F = gas/foil stripping. d, Percent of particles transmitted from injector to analyzer. ‘) Samples measured in the one year period May 1995 through April 1996.
1.6/7 4.5/30 1.2/19 20/195
D. Elmore et ul./Nucl.
Instr. and Meth. in Phys. Res. B I23 (1997169-72
by the faulty belts, filtering was added to signal and power lines entering the accelerator pressure vessel. Commercially available pi filters were used on all of the low voltage wiring entering the accelerator, and filters were constructed for all of the high voltage connections. Operational experience with the initial phase of the upgrade demonstrates great improvement in the useful operating voltage from 6 MV to 7 MV. In addition, the frequency of tank sparks was reduced by more than an order of magnitude. The beam transmission improved from 8% to 20% (for 36Cl) and the terminal ripple reduced by a factor of 5. The electrical filtering has resulted in no damage to the Pelletron power supplies (a fairly common problem) after sparks. In addition, there have been no other equipment failures that have been attributed to tank sparks. These and other improvements have resulted in a factor of two improvement of the AMS precision for 36C1 measurements and a factor of 3 to 5 improvement in sample measuring capacity. The next phase of the upgrade [6] is currently underway. This phase will include rebuilding the beam line between the source and the injector magnet, rebuilding the stripper assembly in the accelerator terminal, and the integration of the controls for this equipment into the VISTA control system which will ultimately control the entire accelerator. Most of the components for the ion source beam line have already been purchased, and custom components are under construction. Most of the drawings for the terminal components are completed. A large pressure test vessel (a used small accelerator tank) is currently being installed. The entire terminal stripper assembly will fit in this test fixture to permit pressure testing and leak checking before the accelerator is shut down for this part of the upgrade. Several critical components for the terminal, such as one of the turbo pumps, are ready for pressure testing. The upgrade of the terminal will include the installation of a fiber-optic communication system to permit computer control of the new terminal components. These improvements are expected to make a substantial improvement in the beam transmission and reduction of interferences for AMS measurements. Initial planning is underway for the installation of the new AMS injector. Only minor changes have been made to the design presented at AMS-6 [6]. This design will provide for the ability to do fast switching once the positive ion analysis portion of the accelerator is also upgraded. The computer control system will be integrated into the accelerator systems during the upgrade to eliminate the need for the construction of manual controls.
71
sample preparation laboratories [8] is complete and preparation techniques for the nuclides listed have been developed for a wide variety of matrices including 36Cl and ‘291 in water, 26Al and “Be in quartz, “Be in soils, and 36C1 in various rock mineral fractions. PRIME Lab chemistry operations are now carried out mainly in two refurbished laboratories in the Department of Chemistry. The design of these labs was based upon ideas used in NASA’s lunar processing laboratory in Houston where one of us (MEL) oversaw construction in l9771979. They were completed in 1995, have airborne particulate counts one-hundredth those of “normal” new chemistry laboratories and are completely equipped for routine processing of low-level samples. These laboratories are completely acid-resistant and, after a year‘s operations, exhibit no evidence for rust anywhere. The larger of the two laboratories, which ultimately will house a class-100 clean room, is chlorine-free and is used for 36Cl preparations. Other radionuclides are processed in the second laboratory. A prototype radiocarbon line has been constructed in the accelerator building and is in operation. Renovation of dual-purpose chemistry laboratories on another floor in the Department of Chemistry is currently under way and should be completed this year. Such laboratories have been and will be used for RNAA (radiochemical neutron activation analysis) studies of extraterrestrial materials, and for radiotracer chemistry associated with biomedical AMS measurements. PRIME Lab’s Chemistry Operations has received 1250 individual samples for single or multiple AMS target preparation during the past three years. From these, 1700 AMS targets were chemically and physically prepared: if we include target preparation for chloride determinations by ID-MS/AMS, the total number of targets increases to almost 1900 targets. About half of the AMS targets have been prepared for analysis of “Cl, while targets for 26Al and “Be analysis amount to 25% and 15%. The remainder includes samples for ‘29I and “‘Ca determinations analytical methods for which are being developed. Water and rock samples are the major matrices analyzed at PRIME Lab‘s Chemistry Operations, comprising about 60% and 25% of the sample volume. Developmental work at PRIME Lab’s Chemistry Operations has focused on: (a) physical and chemical sample preparation of rocks; (b) procedures for separating ““I from diverse matrices; (cl procedures for calcium hydride preparation and storage; and (d) procedures for 14C sample preparation. Activities include isolation and cleaning of mineral separates from rock matrices for “Cl analysis and pretreatment for a variety of materials for 14C analysis, including graphitization.
4. Chemical sample preparation PRIME Lab chemistry operations offers a physical and chemical sample preparation service for the local and international AMS community. Construction of two new
5. Research
program
There are over I25 users of our facility involved in 20 internal and 160 external projects [g]. Purdue-based goals
111.EXISTING FACILITIES
72
D. Elmore et al./Nucl.
Instr. ad Meth. in Phys. Res. B 123 (1997) 69-72
in earth and planetary sciences are to calibrate and develop for using cosmogenic radionuclides to study the history of rocks, soils, meteorites, and ground water through improvements in sample collection methods, chemical separation techniques, and theoretical models. Applications reported at this conference include glacial erosion of bedrock, the glacial history of Indiana, rock erosion rates, glacial, volcanic, and tectonic history of the Andes, Antarctic Meteorites, and the Mocs meteorite strewnfield. Purdue-based goals in the biomedical sciences are to develop methods for tracing aluminum, calcium and carboncontaining compounds in living systems; applications reported here include aluminum uptake in rats, aluminumcontaining adjuvants, and cholesterol. methods
References [l] M. Perry et al., these Proceedings Meth. B 123 (1997) 178.
CAMS-7), Nucl. Ins&. and
121D.L.
Knies and D. Elmore. Nucl. Instr. and Meth. B 92 (1994) 134. 131ES. Michlovich and D. Elmore, PRIME Lab Report PL9303 (Purdue University, West Lafayette, IN, 1993). 141D. Ehnore, L. Dep. R. Flack, M.J. Hawksworth, D.L. Knies, X.2. Ma, E.S. Michlovich, T.E. Miller, K.A. Mueller, F.A. Rickey. P. Sharma, P.C. Simms, H.-J. Woo, M.E. Lipschutz, S. Vogt, M.-S. Wang and MC. Monaghan, Nucl. Instr. and Meth. B 92 (1994) 65. El P. Shanna, D. Elmore, T. Miller and S. Vogt. these Proceedings CAMS-71, Nucl Instr. and Meth. B 123 (1997) 347. [61K.H. Purser, D. Elmore, K.A. Mueller, T.E. Miller, H.R. McK. Hyder and H. Enge, Nucl. Instr. and Meth. B 92 (1994) 69. Nucl. 171S. Vogt, M.-S. Wang, R. Li and M.E. Lipschutz, Instrand Meth. B 92 (1994) 153. b31P. Shanna, D. Elmore and S. Vogt, these Proceedings (AMS71, Nucl. Instr. and Meth. B 123 (1997) 199.