The first application of 39 Ar Accelerator Mass Spectrometry (AMS) at the ATLAS linac of Argonne ... more The first application of 39 Ar Accelerator Mass Spectrometry (AMS) at the ATLAS linac of Argonne National Laboratory (ANL) was to date ocean water samples relevant to oceanographic studies using the gas-filled magnet technique to separate the 39 K-39 Ar isobars. In particular the use of a quartz liner in the plasma chamber of the Electron Cyclotron Resonance (ECR) ion source enabled a 39 K reduction of a factor ~130 compared to previous runs without liners and allowed for our current lowest detection limit of 39 Ar/Ar = 4.2x10 -17 [1]. We are currently working on improving the AMS method for 39 Ar by following two development paths to allow for higher beam currents while lowering 39 K rates. The first option is to modify the design of the quartz liner to provide active water cooling. The second option is to use a thick walled liner of high purity aluminum constructed with an interference fit to the plasma chamber wall. The overall driving force for this AMS project is to search for ...
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2008
The Magnet for Astrophysical Nucleosynthesis studies Through Isobar Separation (MANTIS) system is... more The Magnet for Astrophysical Nucleosynthesis studies Through Isobar Separation (MANTIS) system is the new Accelerator Mass Spectrometry (AMS) set-up created during recent upgrades of the Browne–Buechner spectrograph at the University of Notre Dame. Commissioning measurements performed on the separation of 58Fe–58Ni isobars at 114MeV out of the FN tandem accelerator have shown clear separation, opening the door for a number
Over the past 2.5 years the Browne-Buechner spectrograph at the Nuclear Science Laboratory (NSL) ... more Over the past 2.5 years the Browne-Buechner spectrograph at the Nuclear Science Laboratory (NSL) at the University of Notre Dame has been renovated and its system upgraded to enable operations in the gas-filled mode. In addition to this, a new position sensitive PPAC detector and Ionization counter were developed as the focal plane detector of this system. The upgrade enables operation of the magnet both in the standard as well as in the gas-filled mode for the measurement of specific nuclear reactions of interest in stellar nucleosynthesis. The presentation will focus on the upgrade work that has involved both graduate and undergraduate students as well as the first tests of the system using the separation of the ^58Fe-^58Ni isobars as a benchmark measurement. First results on ^40Ca(alpha, gamma)^44Ti as well as the detection of ^36Cl using AMS in conjunction with the gas-filled technique at Notre Dame will also be presented.
We present a detailed semiclassical study of the propagation of a pair of optical fields in reson... more We present a detailed semiclassical study of the propagation of a pair of optical fields in resonant media with and without adiabatic approximation. In the case of near and on resonance excitation, we show detailed calculations, both analytically and numerically, on the extremely slowly propagating probe pulse and the subsequent regeneration of a pulse via a second pulse from the coupling laser. Further discussions on the adiabatic approximation provide many subtle details of the processes, including the effect on the pulse width of the regenerated optical field. Indeed, all features of the optical pulse regeneration and most of the intricate details of the process can be obtained with the present treatment without invoking a full field theoretical method. For very far off resonance excitation, we show that the analytical solution is nearly detuning independent, a surprising result that is vigorously tested and compared to numerical calculations with very good agreement.
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2013
ABSTRACT AMS detection of the rare isotope 93Zr (t1/2 = 1.6 Ma) has application potential in two ... more ABSTRACT AMS detection of the rare isotope 93Zr (t1/2 = 1.6 Ma) has application potential in two fields of research: a better determination of the 92Zr(n,γ)93Zr cross section, which is relevant in astrophysical modeling of nucleosynthesis processes, and using this radionuclide as tracer in hydrological and radioactive waste studies. The biggest challenge in measuring 93Zr at natural concentrations is adequate separation from its stable isobar 93Nb. The Nuclear Science Laboratory at the University of Notre Dame is developing the capability to measure 93Zr by AMS. Results are reported of first experiments, featuring the combination of a gas-filled magnet with a position-sensitive Parallel Grid Avalanche Counter and a Gas Ionization chamber in this magnet’s focal-plane.
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2011
... Chris Schmitt a , Jay A. LaVerne a , b , Corresponding Author Contact Information , E-mail Th... more ... Chris Schmitt a , Jay A. LaVerne a , b , Corresponding Author Contact Information , E-mail The Corresponding Author , Daniel Robertson a , Matt Bowers a ... for negative ion by cesium sputtering (SNICS), negative ion source and accelerated by the FN Tandem Van de Graff in the ...
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2007
The Nuclear Structure Laboratory (NSL) at the University of Notre Dame installed its Browne-Buech... more The Nuclear Structure Laboratory (NSL) at the University of Notre Dame installed its Browne-Buechner spectrograph in the early 1970s for highly accurate energy measurements of nuclear reactions. Current renovation and upgrading of this spectrograph will enable operation of the magnet in a gas-filled mode, in particular for the study of nuclear reactions with low cross-sections of interest in nuclear astrophysics. One of the principle issues shared by measurements of extremely low abundances in Accelerator Mass Spectrometry (AMS) and nuclear astrophysics is the discrimination between the nuclei of interest and often very intense isobaric background. Recently the AMS technique of the gas-filled magnet has very successfully been used at Argonne National Laboratory (ANL) to overcome this in the study of both environmental noble gas traces (39 Ar) and the measurement of cross-sections of interest in stellar nucleosynthesis i.e. the 62 Ni(n, c) 63 Ni reaction. We hope to extend these techniques further to the observations of astrophysically important reactions such as 40 Ca(a, c) 44 Ti and 78 Kr(a, c) 82 Sr.
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2010
Fast ions lose energy by Coulombic interactions with the electrons of a medium so knowledge of th... more Fast ions lose energy by Coulombic interactions with the electrons of a medium so knowledge of the charge state of the ion is essential to describing a number of fundamental properties including the stopping power of the medium and the range of the ions [1]. Radiation effects and ...
We report on the first measurement of 39 Ar in argon from underground natural gas reservoirs. The... more We report on the first measurement of 39 Ar in argon from underground natural gas reservoirs. The gas stored in the US National Helium Reserve was found to contain a low level of 39 Ar. The ratio of 39 Ar to stable argon was found to be ≤4×10 −17 (84% C.L.), less than 5% the value in atmospheric argon (39 Ar/Ar=8×10 −16). The total quantity of argon currently stored in the National Helium Reserve is estimated at 1000 tons.
Measuring charge state distributions (CSD) of few electron systems, like lithium, through various... more Measuring charge state distributions (CSD) of few electron systems, like lithium, through various targets can provide information to fill gaps in existing models. There is a need to look at target and ion velocity dependence for few electron systems and compare them with ...
Experiments on oscillatory motion are described with three different damping effects. The first e... more Experiments on oscillatory motion are described with three different damping effects. The first experiment is a physical pendulum whose damping mechanism is due to sliding friction; the second is magnetic resistance due to eddy currents; and the third experiment involves a pendulum setup where air resistance is the dominant factor. These three damping mechanisms yield constant (v/| v|), linear, and quadratic resistances in velocity respectively. Approximation methods are described for treating the three damping effects and a general solution is derived for the damping with a very general velocity dependence. A sonic rangefinder is used to record the oscillatory motions of the pendulums. The experimental measurements and theoretical calculations are in a good agreement.
Equilibrium charge state distributions have been measured for 3 -- 7 MeV lithium, boron, and carb... more Equilibrium charge state distributions have been measured for 3 -- 7 MeV lithium, boron, and carbon ions passing through carbon foils. The data are compared to the predictions of several semi-empirical models of charge equilibrium in the $\le $ 1MeV/u regime. The current ...
A recent experiment both at PSI and at Munich on the $^{60}$Fe lifetime points to a T$_{1/2}$ for... more A recent experiment both at PSI and at Munich on the $^{60}$Fe lifetime points to a T$_{1/2}$ for $^{60}$Fe that is possibly 70{\%} higher (ie $\sim $2.6x10$^{6}$ years) than the presently accepted value (1.5x10$^{6}$ years). $^{60}$Fe is mainly produced in core collapse ...
Equilibrium mean charge states have been measured for 37 MeV lithium, boron, and carbon ions pas... more Equilibrium mean charge states have been measured for 37 MeV lithium, boron, and carbon ions passing through thin carbon foils. The data are compared to the predictions of several semiempirical models of charge equilibrium in the ≤1 MeV/u regime. The current work underscores the ...
The first application of 39 Ar Accelerator Mass Spectrometry (AMS) at the ATLAS linac of Argonne ... more The first application of 39 Ar Accelerator Mass Spectrometry (AMS) at the ATLAS linac of Argonne National Laboratory (ANL) was to date ocean water samples relevant to oceanographic studies using the gas-filled magnet technique to separate the 39 K-39 Ar isobars. In particular the use of a quartz liner in the plasma chamber of the Electron Cyclotron Resonance (ECR) ion source enabled a 39 K reduction of a factor ~130 compared to previous runs without liners and allowed for our current lowest detection limit of 39 Ar/Ar = 4.2x10 -17 [1]. We are currently working on improving the AMS method for 39 Ar by following two development paths to allow for higher beam currents while lowering 39 K rates. The first option is to modify the design of the quartz liner to provide active water cooling. The second option is to use a thick walled liner of high purity aluminum constructed with an interference fit to the plasma chamber wall. The overall driving force for this AMS project is to search for ...
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2008
The Magnet for Astrophysical Nucleosynthesis studies Through Isobar Separation (MANTIS) system is... more The Magnet for Astrophysical Nucleosynthesis studies Through Isobar Separation (MANTIS) system is the new Accelerator Mass Spectrometry (AMS) set-up created during recent upgrades of the Browne–Buechner spectrograph at the University of Notre Dame. Commissioning measurements performed on the separation of 58Fe–58Ni isobars at 114MeV out of the FN tandem accelerator have shown clear separation, opening the door for a number
Over the past 2.5 years the Browne-Buechner spectrograph at the Nuclear Science Laboratory (NSL) ... more Over the past 2.5 years the Browne-Buechner spectrograph at the Nuclear Science Laboratory (NSL) at the University of Notre Dame has been renovated and its system upgraded to enable operations in the gas-filled mode. In addition to this, a new position sensitive PPAC detector and Ionization counter were developed as the focal plane detector of this system. The upgrade enables operation of the magnet both in the standard as well as in the gas-filled mode for the measurement of specific nuclear reactions of interest in stellar nucleosynthesis. The presentation will focus on the upgrade work that has involved both graduate and undergraduate students as well as the first tests of the system using the separation of the ^58Fe-^58Ni isobars as a benchmark measurement. First results on ^40Ca(alpha, gamma)^44Ti as well as the detection of ^36Cl using AMS in conjunction with the gas-filled technique at Notre Dame will also be presented.
We present a detailed semiclassical study of the propagation of a pair of optical fields in reson... more We present a detailed semiclassical study of the propagation of a pair of optical fields in resonant media with and without adiabatic approximation. In the case of near and on resonance excitation, we show detailed calculations, both analytically and numerically, on the extremely slowly propagating probe pulse and the subsequent regeneration of a pulse via a second pulse from the coupling laser. Further discussions on the adiabatic approximation provide many subtle details of the processes, including the effect on the pulse width of the regenerated optical field. Indeed, all features of the optical pulse regeneration and most of the intricate details of the process can be obtained with the present treatment without invoking a full field theoretical method. For very far off resonance excitation, we show that the analytical solution is nearly detuning independent, a surprising result that is vigorously tested and compared to numerical calculations with very good agreement.
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2013
ABSTRACT AMS detection of the rare isotope 93Zr (t1/2 = 1.6 Ma) has application potential in two ... more ABSTRACT AMS detection of the rare isotope 93Zr (t1/2 = 1.6 Ma) has application potential in two fields of research: a better determination of the 92Zr(n,γ)93Zr cross section, which is relevant in astrophysical modeling of nucleosynthesis processes, and using this radionuclide as tracer in hydrological and radioactive waste studies. The biggest challenge in measuring 93Zr at natural concentrations is adequate separation from its stable isobar 93Nb. The Nuclear Science Laboratory at the University of Notre Dame is developing the capability to measure 93Zr by AMS. Results are reported of first experiments, featuring the combination of a gas-filled magnet with a position-sensitive Parallel Grid Avalanche Counter and a Gas Ionization chamber in this magnet’s focal-plane.
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2011
... Chris Schmitt a , Jay A. LaVerne a , b , Corresponding Author Contact Information , E-mail Th... more ... Chris Schmitt a , Jay A. LaVerne a , b , Corresponding Author Contact Information , E-mail The Corresponding Author , Daniel Robertson a , Matt Bowers a ... for negative ion by cesium sputtering (SNICS), negative ion source and accelerated by the FN Tandem Van de Graff in the ...
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2007
The Nuclear Structure Laboratory (NSL) at the University of Notre Dame installed its Browne-Buech... more The Nuclear Structure Laboratory (NSL) at the University of Notre Dame installed its Browne-Buechner spectrograph in the early 1970s for highly accurate energy measurements of nuclear reactions. Current renovation and upgrading of this spectrograph will enable operation of the magnet in a gas-filled mode, in particular for the study of nuclear reactions with low cross-sections of interest in nuclear astrophysics. One of the principle issues shared by measurements of extremely low abundances in Accelerator Mass Spectrometry (AMS) and nuclear astrophysics is the discrimination between the nuclei of interest and often very intense isobaric background. Recently the AMS technique of the gas-filled magnet has very successfully been used at Argonne National Laboratory (ANL) to overcome this in the study of both environmental noble gas traces (39 Ar) and the measurement of cross-sections of interest in stellar nucleosynthesis i.e. the 62 Ni(n, c) 63 Ni reaction. We hope to extend these techniques further to the observations of astrophysically important reactions such as 40 Ca(a, c) 44 Ti and 78 Kr(a, c) 82 Sr.
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2010
Fast ions lose energy by Coulombic interactions with the electrons of a medium so knowledge of th... more Fast ions lose energy by Coulombic interactions with the electrons of a medium so knowledge of the charge state of the ion is essential to describing a number of fundamental properties including the stopping power of the medium and the range of the ions [1]. Radiation effects and ...
We report on the first measurement of 39 Ar in argon from underground natural gas reservoirs. The... more We report on the first measurement of 39 Ar in argon from underground natural gas reservoirs. The gas stored in the US National Helium Reserve was found to contain a low level of 39 Ar. The ratio of 39 Ar to stable argon was found to be ≤4×10 −17 (84% C.L.), less than 5% the value in atmospheric argon (39 Ar/Ar=8×10 −16). The total quantity of argon currently stored in the National Helium Reserve is estimated at 1000 tons.
Measuring charge state distributions (CSD) of few electron systems, like lithium, through various... more Measuring charge state distributions (CSD) of few electron systems, like lithium, through various targets can provide information to fill gaps in existing models. There is a need to look at target and ion velocity dependence for few electron systems and compare them with ...
Experiments on oscillatory motion are described with three different damping effects. The first e... more Experiments on oscillatory motion are described with three different damping effects. The first experiment is a physical pendulum whose damping mechanism is due to sliding friction; the second is magnetic resistance due to eddy currents; and the third experiment involves a pendulum setup where air resistance is the dominant factor. These three damping mechanisms yield constant (v/| v|), linear, and quadratic resistances in velocity respectively. Approximation methods are described for treating the three damping effects and a general solution is derived for the damping with a very general velocity dependence. A sonic rangefinder is used to record the oscillatory motions of the pendulums. The experimental measurements and theoretical calculations are in a good agreement.
Equilibrium charge state distributions have been measured for 3 -- 7 MeV lithium, boron, and carb... more Equilibrium charge state distributions have been measured for 3 -- 7 MeV lithium, boron, and carbon ions passing through carbon foils. The data are compared to the predictions of several semi-empirical models of charge equilibrium in the $\le $ 1MeV/u regime. The current ...
A recent experiment both at PSI and at Munich on the $^{60}$Fe lifetime points to a T$_{1/2}$ for... more A recent experiment both at PSI and at Munich on the $^{60}$Fe lifetime points to a T$_{1/2}$ for $^{60}$Fe that is possibly 70{\%} higher (ie $\sim $2.6x10$^{6}$ years) than the presently accepted value (1.5x10$^{6}$ years). $^{60}$Fe is mainly produced in core collapse ...
Equilibrium mean charge states have been measured for 37 MeV lithium, boron, and carbon ions pas... more Equilibrium mean charge states have been measured for 37 MeV lithium, boron, and carbon ions passing through thin carbon foils. The data are compared to the predictions of several semiempirical models of charge equilibrium in the ≤1 MeV/u regime. The current work underscores the ...
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