Nadeesha Gamage | Central Michigan University (original) (raw)

Papers by Nadeesha Gamage

Cornell University - arXiv, Feb 25, 2022

Background: An ultra-low Q value β-decay can occur from a parent nuclide to an excited nuclear st... more Background: An ultra-low Q value β-decay can occur from a parent nuclide to an excited nuclear state in the daughter such that QUL 1 keV. These decay processes are of interest for nuclear β-decay theory and as potential candidates in neutrino mass determination experiments. To date, only one ultra-low Q value β-decay has been observed-that of 115 In with Q β = 147(10) eV. A number of other potential candidates exist, but improved mass measurements are necessary to determine if these decay channels are energetically allowed and, in fact, ultra-low. Purpose: To perform precise β-decay Q value measurements of 112,113 Ag and 115 Cd and to use them in combination with nuclear energy level data for the daughter isotopes 112,113 Cd and 115 In to determine if the potential ultra-low Q value β-decay branches of 112,113 Ag and 115 Cd are energetically allowed and 1 keV. Method: The Canadian Penning Trap at Argonne National Laboratory was used to measure the cyclotron frequency ratios of singly-charged 112,113 Ag and 115 Cd ions with respect to their daughters 112,113 Cd and 115 In. From these measurements, the ground-state to ground-state β-decay Q values were obtained. Results: The 112 Ag → 112 Cd, 113 Ag → 113 Cd, and 115 Cd → 115 In β-decay Q values were measured to be Q β (112 Ag) = 3990.16(22) keV, Q β (113 Ag) = 2085.7(4.6) keV, and Q β (115 Cd) = 1451.36(34) keV. These results were compared to energies of excited states in 112 Cd at 3997.75(14) keV, 113 Cd at 2015.6(2.5) and 2080(10) keV, and 115 In at 1448.787(9) keV, resulting in precise QUL values for the potential decay channels of-7.59(26) keV, 6(11) keV, and 2.57(34) keV, respectively. Conclusion: The potential ultra-low Q value decays of 112 Ag and 115 Cd have been ruled out. 113 Ag is still a possible candidate until a more precise measurement of the 2080(10) keV, 1/2 + state of 113 Cd is available. In the course of this work we have found the ground state mass of 113 Ag reported in the 2020 Atomic Mass Evaluation [Wang, et al., Chin. Phys. C 45, 030003 (2021)] to be lower than our measurement by 69(17) keV (a 4σ discrepancy).

Bulletin of the American Physical Society, Oct 12, 2021

Bulletin of the American Physical Society, 2018

Bulletin of the American Physical Society, 2018

Physical Review C, 2016

Using Penning trap mass spectrometry, we have performed a precise determination of the Q value fo... more Using Penning trap mass spectrometry, we have performed a precise determination of the Q value for the highly-forbidden β-decay of 113 Cd. An independent measurement of the Q value fixes the endpoint energy in a fit to the 113 Cd β-decay spectrum. This provides a strong test of systematics for detectors that have observed this decay, such as those developed for ββ-decay searches in cadmium and other isotopes. It will also aid in the theoretical description of the β-decay spectrum. The result, Q β = 323.89(27) keV, agrees at the 1.3σ level with the value obtained from the 2012 Atomic Mass Evaluation [Chin. Phys. C 36, 1603 (2012)], but is a factor of almost four more precise. We also report improved values for the atomic masses of 113 Cd, 113 In and 112 Cd.

APS Division of Nuclear Physics Meeting Abstracts, 2019

Ultra-low" Q value β decays are referred to as such due to their low decay energies of less than ... more Ultra-low" Q value β decays are referred to as such due to their low decay energies of less than ∼1 keV. Such a low energy decay is possible when the parent nucleus decays into an excited state in the daughter, with an energy close to that of the Q value. These decays are of interest as potential new candidates for neutrino mass determination experiments and as a testing ground for studies of atomic interference effects in the nuclear decay process. In this paper, we provide an updated evaluation of atomic mass data and nuclear energy level data to identify potential ultra-low Q value β decay candidates. For many of these candidates, more precise and accurate atomic mass data is needed to determine if the Q value of the potential ultra-low decay branch is energetically allowed and in fact ultra-low. The precise atomic mass measurements can be achieved via Penning trap mass spectrometry.

APS Division of Nuclear Physics Meeting Abstracts, 2019

Bulletin of the American Physical Society, 2018

Bulletin of the American Physical Society, 2017

LOW ENERGY BEAM ION TRAP TEAM-Over the last several decades, extremely sensitive, ultra-low backg... more LOW ENERGY BEAM ION TRAP TEAM-Over the last several decades, extremely sensitive, ultra-low background beta and gamma detection techniques have been developed. These techniques have enabled the observation of very rare processes, such as highly forbidden beta decays e.g. of 113Cd, 50V and 138La. Half-life measurements of highly forbidden beta decays provide a testing ground for theoretical nuclear models, and the comparison of calculated and measured energy spectra could enable a determination of the values of the weak coupling constants. Precision Q-value measurements also allow for systematic tests of the beta-particle detection techniques. We will present the results and current status of Q value determinations for highly forbidden beta decays. The Q values, the mass difference between parent and daughter nuclides, are measured using the high precision Penning trap mass spectrometer LEBIT at the National Superconducting Cyclotron Laboratory.

Hyperfine Interactions, 2019

At Central Michigan University, we are developing a high-precision Penning trap mass spectrometer... more At Central Michigan University, we are developing a high-precision Penning trap mass spectrometer (CHIP-TRAP) for precise mass measurements with stable and long-lived isotopes. Ions will be produced using external ion sources and then transported to the Penning trap at low energy using electrostatic ion optics. Ion sources that will be utilized with CHIP-TRAP include a laser ablation ion source (LAS) that has already been commissioned, and a low current Penning ion trap (PIT) source that is currently being developed. The LAS enables ion production from solid targets via ablation and ionization with a high-powered laser pulse. The PIT source is a novel Penning ionization gauge (PIG) type source, consisting of a 0.55 T NdFeB ring magnet, cylindrical Penning trap, and low current thermal electron emitter that enables ion production via electron impact ionization of gaseous samples. For both ion sources, small bunches of ∼100-1000 ions can be produced from a minimal sample of source material. The ion bunches are then transported along the CHIP-TRAP beamline, where time-of-flight mass filtering can be performed before they are captured in the CHIP-TRAP Penning traps.

Ultra-low" Q value β decays are referred to as such due to their low decay energies of less than ... more Ultra-low" Q value β decays are referred to as such due to their low decay energies of less than ∼1 keV. Such a low energy decay is possible when the parent nucleus decays into an excited state in the daughter, with an energy close to that of the Q value. These decays are of interest as potential new candidates for neutrino mass determination experiments and as a testing ground for studies of atomic interference effects in the nuclear decay process. In this paper, we provide an updated evaluation of atomic mass data and nuclear energy level data to identify potential ultra-low Q value β decay candidates. For many of these candidates, more precise and accurate atomic mass data is needed to determine if the Q value of the potential ultra-low decay branch is energetically allowed and in fact ultra-low. The precise atomic mass measurements can be achieved via Penning trap mass spectrometry.

Physical Review C, 2019

Background: Ultra-low Q-value β-decays are interesting processes to study with potential applicat... more Background: Ultra-low Q-value β-decays are interesting processes to study with potential applications to nuclear β-decay theory and neutrino physics. While a number of potential ultra-low Q-value β-decay candidates exist, improved mass measurements are necessary to determine which of these are energetically allowed. Purpose: To perform precise atomic mass measurements of 89 Y and 139 La. Use these new measurements along with the precisely known atomic masses of 89 Sr and 139 Ba and nuclear energy level data for 89 Y and 139 La to determine if there could be an ultra-low Q-value decay branch in the β-decay of 89 Sr → 89 Y or 139 Ba → 139 La. Method: High-precision Penning trap mass spectrometry was used to determine the atomic mass of 89 Y and 139 La, from which β-decay Q-values for 89 Sr and 139 Ba were obtained. Results: The 89 Sr → 89 Y and 139 Ba → 139 La β-decay Q-values were measured to be QSr = 1502.20(0.35) keV and QBa = 2308.37(0.68) keV. These results were compared to energies of excited states in 89 Y at 1507.4(0.1) keV, and in 139 La at 2310(19) keV and 2313(1) keV to determine Q-values of-5.20(0.37) keV for the potential ultra-low β-decay branch of 89 Sr and-1.6(19.0) keV and-4.6(1.2) keV for those of 139 Ba. Conclusion: The potential ultra-low Q-value decay branch of 89 Sr to the 89 Y (3/2 − , 1507.4 keV) state is energetically forbidden and has been ruled out. The potential ultra-low Q-value decay branch of 139 Ba to the 2313 keV state in 139 La with unknown J π has also been ruled out at the 4σ level, while more precise energy level data is needed for the 139 La (1/2 + , 2310 keV) state to determine if an ultra-low Q-value β-decay branch to this state is energetically allowed.

APS Division of Nuclear Physics Meeting Abstracts, 2019

Bulletin of the American Physical Society, 2018

Bulletin of the American Physical Society, 2017

LOW ENERGY BEAM ION TRAP TEAM-Over the last several decades, extremely sensitive, ultra-low backg... more LOW ENERGY BEAM ION TRAP TEAM-Over the last several decades, extremely sensitive, ultra-low background beta and gamma detection techniques have been developed. These techniques have enabled the observation of very rare processes, such as highly forbidden beta decays e.g. of 113Cd, 50V and 138La. Half-life measurements of highly forbidden beta decays provide a testing ground for theoretical nuclear models, and the comparison of calculated and measured energy spectra could enable a determination of the values of the weak coupling constants. Precision Q-value measurements also allow for systematic tests of the beta-particle detection techniques. We will present the results and current status of Q value determinations for highly forbidden beta decays. The Q values, the mass difference between parent and daughter nuclides, are measured using the high precision Penning trap mass spectrometer LEBIT at the National Superconducting Cyclotron Laboratory.

Hyperfine Interactions, 2019

At Central Michigan University, we are developing a high-precision Penning trap mass spectrometer... more At Central Michigan University, we are developing a high-precision Penning trap mass spectrometer (CHIP-TRAP) for precise mass measurements with stable and long-lived isotopes. Ions will be produced using external ion sources and then transported to the Penning trap at low energy using electrostatic ion optics. Ion sources that will be utilized with CHIP-TRAP include a laser ablation ion source (LAS) that has already been commissioned, and a low current Penning ion trap (PIT) source that is currently being developed. The LAS enables ion production from solid targets via ablation and ionization with a high-powered laser pulse. The PIT source is a novel Penning ionization gauge (PIG) type source, consisting of a 0.55 T NdFeB ring magnet, cylindrical Penning trap, and low current thermal electron emitter that enables ion production via electron impact ionization of gaseous samples. For both ion sources, small bunches of ∼100-1000 ions can be produced from a minimal sample of source material. The ion bunches are then transported along the CHIP-TRAP beamline, where time-of-flight mass filtering can be performed before they are captured in the CHIP-TRAP Penning traps.

Physical Review C, 2019

Background: Ultra-low Q-value β-decays are interesting processes to study with potential applicat... more Background: Ultra-low Q-value β-decays are interesting processes to study with potential applications to nuclear β-decay theory and neutrino physics. While a number of potential ultra-low Q-value β-decay candidates exist, improved mass measurements are necessary to determine which of these are energetically allowed. Purpose: To perform precise atomic mass measurements of 89 Y and 139 La. Use these new measurements along with the precisely known atomic masses of 89 Sr and 139 Ba and nuclear energy level data for 89 Y and 139 La to determine if there could be an ultra-low Q-value decay branch in the β-decay of 89 Sr → 89 Y or 139 Ba → 139 La. Method: High-precision Penning trap mass spectrometry was used to determine the atomic mass of 89 Y and 139 La, from which β-decay Q-values for 89 Sr and 139 Ba were obtained. Results: The 89 Sr → 89 Y and 139 Ba → 139 La β-decay Q-values were measured to be QSr = 1502.20(0.35) keV and QBa = 2308.37(0.68) keV. These results were compared to energies of excited states in 89 Y at 1507.4(0.1) keV, and in 139 La at 2310(19) keV and 2313(1) keV to determine Q-values of-5.20(0.37) keV for the potential ultra-low β-decay branch of 89 Sr and-1.6(19.0) keV and-4.6(1.2) keV for those of 139 Ba. Conclusion: The potential ultra-low Q-value decay branch of 89 Sr to the 89 Y (3/2 − , 1507.4 keV) state is energetically forbidden and has been ruled out. The potential ultra-low Q-value decay branch of 139 Ba to the 2313 keV state in 139 La with unknown J π has also been ruled out at the 4σ level, while more precise energy level data is needed for the 139 La (1/2 + , 2310 keV) state to determine if an ultra-low Q-value β-decay branch to this state is energetically allowed.

Hyperfine Interactions, 2019

Among the wide energy range of β decays, there can exist decays with Q values as low as a few hun... more Among the wide energy range of β decays, there can exist decays with Q values as low as a few hundred eV. These decays can occur when the parent decays to a excited state in the daughter nucleus. Such decays have been called "ultra-low" Q value β decays. Their application is mainly twofold: (1) they are of interest as potential candidates for neutrino mass determination experiments, and (2) they provide a testing ground for theoretical studies of atomic interference effects in the nuclear decay process. In this work we have identified a number of such potential candidates by analyzing the most recent atomic mass and nuclear energy level data. To determine if an ultra-low Q value β decay branch is energetically allowed for these candidates, more precise and accurate data for the Q value of the ultra-low decay branch is needed. In most cases, this requires more precise atomic mass measurements for the parent and/or daughter atoms. These requirements can be met using Penning trap mass spectrometry.

Hyperfine Interactions, 2019

Among the wide energy range of β decays, there can exist decays with Q values as low as a few hun... more Among the wide energy range of β decays, there can exist decays with Q values as low as a few hundred eV. These decays can occur when the parent decays to a excited state in the daughter nucleus. Such decays have been called "ultra-low" Q value β decays. Their application is mainly twofold: (1) they are of interest as potential candidates for neutrino mass determination experiments, and (2) they provide a testing ground for theoretical studies of atomic interference effects in the nuclear decay process. In this work we have identified a number of such potential candidates by analyzing the most recent atomic mass and nuclear energy level data. To determine if an ultra-low Q value β decay branch is energetically allowed for these candidates, more precise and accurate data for the Q value of the ultra-low decay branch is needed. In most cases, this requires more precise atomic mass measurements for the parent and/or daughter atoms. These requirements can be met using Penning trap mass spectrometry.

Cornell University - arXiv, Feb 25, 2022

Background: An ultra-low Q value β-decay can occur from a parent nuclide to an excited nuclear st... more Background: An ultra-low Q value β-decay can occur from a parent nuclide to an excited nuclear state in the daughter such that QUL 1 keV. These decay processes are of interest for nuclear β-decay theory and as potential candidates in neutrino mass determination experiments. To date, only one ultra-low Q value β-decay has been observed-that of 115 In with Q β = 147(10) eV. A number of other potential candidates exist, but improved mass measurements are necessary to determine if these decay channels are energetically allowed and, in fact, ultra-low. Purpose: To perform precise β-decay Q value measurements of 112,113 Ag and 115 Cd and to use them in combination with nuclear energy level data for the daughter isotopes 112,113 Cd and 115 In to determine if the potential ultra-low Q value β-decay branches of 112,113 Ag and 115 Cd are energetically allowed and 1 keV. Method: The Canadian Penning Trap at Argonne National Laboratory was used to measure the cyclotron frequency ratios of singly-charged 112,113 Ag and 115 Cd ions with respect to their daughters 112,113 Cd and 115 In. From these measurements, the ground-state to ground-state β-decay Q values were obtained. Results: The 112 Ag → 112 Cd, 113 Ag → 113 Cd, and 115 Cd → 115 In β-decay Q values were measured to be Q β (112 Ag) = 3990.16(22) keV, Q β (113 Ag) = 2085.7(4.6) keV, and Q β (115 Cd) = 1451.36(34) keV. These results were compared to energies of excited states in 112 Cd at 3997.75(14) keV, 113 Cd at 2015.6(2.5) and 2080(10) keV, and 115 In at 1448.787(9) keV, resulting in precise QUL values for the potential decay channels of-7.59(26) keV, 6(11) keV, and 2.57(34) keV, respectively. Conclusion: The potential ultra-low Q value decays of 112 Ag and 115 Cd have been ruled out. 113 Ag is still a possible candidate until a more precise measurement of the 2080(10) keV, 1/2 + state of 113 Cd is available. In the course of this work we have found the ground state mass of 113 Ag reported in the 2020 Atomic Mass Evaluation [Wang, et al., Chin. Phys. C 45, 030003 (2021)] to be lower than our measurement by 69(17) keV (a 4σ discrepancy).

Bulletin of the American Physical Society, Oct 12, 2021

Bulletin of the American Physical Society, 2018

Bulletin of the American Physical Society, 2018

Physical Review C, 2016

Using Penning trap mass spectrometry, we have performed a precise determination of the Q value fo... more Using Penning trap mass spectrometry, we have performed a precise determination of the Q value for the highly-forbidden β-decay of 113 Cd. An independent measurement of the Q value fixes the endpoint energy in a fit to the 113 Cd β-decay spectrum. This provides a strong test of systematics for detectors that have observed this decay, such as those developed for ββ-decay searches in cadmium and other isotopes. It will also aid in the theoretical description of the β-decay spectrum. The result, Q β = 323.89(27) keV, agrees at the 1.3σ level with the value obtained from the 2012 Atomic Mass Evaluation [Chin. Phys. C 36, 1603 (2012)], but is a factor of almost four more precise. We also report improved values for the atomic masses of 113 Cd, 113 In and 112 Cd.

APS Division of Nuclear Physics Meeting Abstracts, 2019

Ultra-low" Q value β decays are referred to as such due to their low decay energies of less than ... more Ultra-low" Q value β decays are referred to as such due to their low decay energies of less than ∼1 keV. Such a low energy decay is possible when the parent nucleus decays into an excited state in the daughter, with an energy close to that of the Q value. These decays are of interest as potential new candidates for neutrino mass determination experiments and as a testing ground for studies of atomic interference effects in the nuclear decay process. In this paper, we provide an updated evaluation of atomic mass data and nuclear energy level data to identify potential ultra-low Q value β decay candidates. For many of these candidates, more precise and accurate atomic mass data is needed to determine if the Q value of the potential ultra-low decay branch is energetically allowed and in fact ultra-low. The precise atomic mass measurements can be achieved via Penning trap mass spectrometry.

APS Division of Nuclear Physics Meeting Abstracts, 2019

Bulletin of the American Physical Society, 2018

Bulletin of the American Physical Society, 2017

LOW ENERGY BEAM ION TRAP TEAM-Over the last several decades, extremely sensitive, ultra-low backg... more LOW ENERGY BEAM ION TRAP TEAM-Over the last several decades, extremely sensitive, ultra-low background beta and gamma detection techniques have been developed. These techniques have enabled the observation of very rare processes, such as highly forbidden beta decays e.g. of 113Cd, 50V and 138La. Half-life measurements of highly forbidden beta decays provide a testing ground for theoretical nuclear models, and the comparison of calculated and measured energy spectra could enable a determination of the values of the weak coupling constants. Precision Q-value measurements also allow for systematic tests of the beta-particle detection techniques. We will present the results and current status of Q value determinations for highly forbidden beta decays. The Q values, the mass difference between parent and daughter nuclides, are measured using the high precision Penning trap mass spectrometer LEBIT at the National Superconducting Cyclotron Laboratory.

Hyperfine Interactions, 2019

At Central Michigan University, we are developing a high-precision Penning trap mass spectrometer... more At Central Michigan University, we are developing a high-precision Penning trap mass spectrometer (CHIP-TRAP) for precise mass measurements with stable and long-lived isotopes. Ions will be produced using external ion sources and then transported to the Penning trap at low energy using electrostatic ion optics. Ion sources that will be utilized with CHIP-TRAP include a laser ablation ion source (LAS) that has already been commissioned, and a low current Penning ion trap (PIT) source that is currently being developed. The LAS enables ion production from solid targets via ablation and ionization with a high-powered laser pulse. The PIT source is a novel Penning ionization gauge (PIG) type source, consisting of a 0.55 T NdFeB ring magnet, cylindrical Penning trap, and low current thermal electron emitter that enables ion production via electron impact ionization of gaseous samples. For both ion sources, small bunches of ∼100-1000 ions can be produced from a minimal sample of source material. The ion bunches are then transported along the CHIP-TRAP beamline, where time-of-flight mass filtering can be performed before they are captured in the CHIP-TRAP Penning traps.

Ultra-low" Q value β decays are referred to as such due to their low decay energies of less than ... more Ultra-low" Q value β decays are referred to as such due to their low decay energies of less than ∼1 keV. Such a low energy decay is possible when the parent nucleus decays into an excited state in the daughter, with an energy close to that of the Q value. These decays are of interest as potential new candidates for neutrino mass determination experiments and as a testing ground for studies of atomic interference effects in the nuclear decay process. In this paper, we provide an updated evaluation of atomic mass data and nuclear energy level data to identify potential ultra-low Q value β decay candidates. For many of these candidates, more precise and accurate atomic mass data is needed to determine if the Q value of the potential ultra-low decay branch is energetically allowed and in fact ultra-low. The precise atomic mass measurements can be achieved via Penning trap mass spectrometry.

Physical Review C, 2019

Background: Ultra-low Q-value β-decays are interesting processes to study with potential applicat... more Background: Ultra-low Q-value β-decays are interesting processes to study with potential applications to nuclear β-decay theory and neutrino physics. While a number of potential ultra-low Q-value β-decay candidates exist, improved mass measurements are necessary to determine which of these are energetically allowed. Purpose: To perform precise atomic mass measurements of 89 Y and 139 La. Use these new measurements along with the precisely known atomic masses of 89 Sr and 139 Ba and nuclear energy level data for 89 Y and 139 La to determine if there could be an ultra-low Q-value decay branch in the β-decay of 89 Sr → 89 Y or 139 Ba → 139 La. Method: High-precision Penning trap mass spectrometry was used to determine the atomic mass of 89 Y and 139 La, from which β-decay Q-values for 89 Sr and 139 Ba were obtained. Results: The 89 Sr → 89 Y and 139 Ba → 139 La β-decay Q-values were measured to be QSr = 1502.20(0.35) keV and QBa = 2308.37(0.68) keV. These results were compared to energies of excited states in 89 Y at 1507.4(0.1) keV, and in 139 La at 2310(19) keV and 2313(1) keV to determine Q-values of-5.20(0.37) keV for the potential ultra-low β-decay branch of 89 Sr and-1.6(19.0) keV and-4.6(1.2) keV for those of 139 Ba. Conclusion: The potential ultra-low Q-value decay branch of 89 Sr to the 89 Y (3/2 − , 1507.4 keV) state is energetically forbidden and has been ruled out. The potential ultra-low Q-value decay branch of 139 Ba to the 2313 keV state in 139 La with unknown J π has also been ruled out at the 4σ level, while more precise energy level data is needed for the 139 La (1/2 + , 2310 keV) state to determine if an ultra-low Q-value β-decay branch to this state is energetically allowed.

APS Division of Nuclear Physics Meeting Abstracts, 2019

Bulletin of the American Physical Society, 2018

Bulletin of the American Physical Society, 2017

LOW ENERGY BEAM ION TRAP TEAM-Over the last several decades, extremely sensitive, ultra-low backg... more LOW ENERGY BEAM ION TRAP TEAM-Over the last several decades, extremely sensitive, ultra-low background beta and gamma detection techniques have been developed. These techniques have enabled the observation of very rare processes, such as highly forbidden beta decays e.g. of 113Cd, 50V and 138La. Half-life measurements of highly forbidden beta decays provide a testing ground for theoretical nuclear models, and the comparison of calculated and measured energy spectra could enable a determination of the values of the weak coupling constants. Precision Q-value measurements also allow for systematic tests of the beta-particle detection techniques. We will present the results and current status of Q value determinations for highly forbidden beta decays. The Q values, the mass difference between parent and daughter nuclides, are measured using the high precision Penning trap mass spectrometer LEBIT at the National Superconducting Cyclotron Laboratory.

Hyperfine Interactions, 2019

At Central Michigan University, we are developing a high-precision Penning trap mass spectrometer... more At Central Michigan University, we are developing a high-precision Penning trap mass spectrometer (CHIP-TRAP) for precise mass measurements with stable and long-lived isotopes. Ions will be produced using external ion sources and then transported to the Penning trap at low energy using electrostatic ion optics. Ion sources that will be utilized with CHIP-TRAP include a laser ablation ion source (LAS) that has already been commissioned, and a low current Penning ion trap (PIT) source that is currently being developed. The LAS enables ion production from solid targets via ablation and ionization with a high-powered laser pulse. The PIT source is a novel Penning ionization gauge (PIG) type source, consisting of a 0.55 T NdFeB ring magnet, cylindrical Penning trap, and low current thermal electron emitter that enables ion production via electron impact ionization of gaseous samples. For both ion sources, small bunches of ∼100-1000 ions can be produced from a minimal sample of source material. The ion bunches are then transported along the CHIP-TRAP beamline, where time-of-flight mass filtering can be performed before they are captured in the CHIP-TRAP Penning traps.

Physical Review C, 2019

Background: Ultra-low Q-value β-decays are interesting processes to study with potential applicat... more Background: Ultra-low Q-value β-decays are interesting processes to study with potential applications to nuclear β-decay theory and neutrino physics. While a number of potential ultra-low Q-value β-decay candidates exist, improved mass measurements are necessary to determine which of these are energetically allowed. Purpose: To perform precise atomic mass measurements of 89 Y and 139 La. Use these new measurements along with the precisely known atomic masses of 89 Sr and 139 Ba and nuclear energy level data for 89 Y and 139 La to determine if there could be an ultra-low Q-value decay branch in the β-decay of 89 Sr → 89 Y or 139 Ba → 139 La. Method: High-precision Penning trap mass spectrometry was used to determine the atomic mass of 89 Y and 139 La, from which β-decay Q-values for 89 Sr and 139 Ba were obtained. Results: The 89 Sr → 89 Y and 139 Ba → 139 La β-decay Q-values were measured to be QSr = 1502.20(0.35) keV and QBa = 2308.37(0.68) keV. These results were compared to energies of excited states in 89 Y at 1507.4(0.1) keV, and in 139 La at 2310(19) keV and 2313(1) keV to determine Q-values of-5.20(0.37) keV for the potential ultra-low β-decay branch of 89 Sr and-1.6(19.0) keV and-4.6(1.2) keV for those of 139 Ba. Conclusion: The potential ultra-low Q-value decay branch of 89 Sr to the 89 Y (3/2 − , 1507.4 keV) state is energetically forbidden and has been ruled out. The potential ultra-low Q-value decay branch of 139 Ba to the 2313 keV state in 139 La with unknown J π has also been ruled out at the 4σ level, while more precise energy level data is needed for the 139 La (1/2 + , 2310 keV) state to determine if an ultra-low Q-value β-decay branch to this state is energetically allowed.

Hyperfine Interactions, 2019

Among the wide energy range of β decays, there can exist decays with Q values as low as a few hun... more Among the wide energy range of β decays, there can exist decays with Q values as low as a few hundred eV. These decays can occur when the parent decays to a excited state in the daughter nucleus. Such decays have been called "ultra-low" Q value β decays. Their application is mainly twofold: (1) they are of interest as potential candidates for neutrino mass determination experiments, and (2) they provide a testing ground for theoretical studies of atomic interference effects in the nuclear decay process. In this work we have identified a number of such potential candidates by analyzing the most recent atomic mass and nuclear energy level data. To determine if an ultra-low Q value β decay branch is energetically allowed for these candidates, more precise and accurate data for the Q value of the ultra-low decay branch is needed. In most cases, this requires more precise atomic mass measurements for the parent and/or daughter atoms. These requirements can be met using Penning trap mass spectrometry.

Hyperfine Interactions, 2019

Among the wide energy range of β decays, there can exist decays with Q values as low as a few hun... more Among the wide energy range of β decays, there can exist decays with Q values as low as a few hundred eV. These decays can occur when the parent decays to a excited state in the daughter nucleus. Such decays have been called "ultra-low" Q value β decays. Their application is mainly twofold: (1) they are of interest as potential candidates for neutrino mass determination experiments, and (2) they provide a testing ground for theoretical studies of atomic interference effects in the nuclear decay process. In this work we have identified a number of such potential candidates by analyzing the most recent atomic mass and nuclear energy level data. To determine if an ultra-low Q value β decay branch is energetically allowed for these candidates, more precise and accurate data for the Q value of the ultra-low decay branch is needed. In most cases, this requires more precise atomic mass measurements for the parent and/or daughter atoms. These requirements can be met using Penning trap mass spectrometry.