15 results on '"Alexander Dombos"'
Search Results
2. β -decay feeding intensity distributions for Nb103,104m
- Author
-
Benjamin P. Crider, Thomas Baumann, Sean Liddick, F. Naqvi, C. J. Prokop, E. Kwan, S. J. Quinn, Chandana Sumithrarachchi, Alejandro Algora, T. N. Ginter, J. Gombas, D.P. Scriven, J. Pereira, Alexander Dombos, Anna Simon, A. Spyrou, Paul DeYoung, Stephanie Lyons, E. M. Ney, W.-J. Ong, and Jonathan Engel
- Subjects
Physics ,Isotope ,Total absorption spectroscopy ,010308 nuclear & particles physics ,Nuclear structure ,Electron ,01 natural sciences ,Distribution (mathematics) ,0103 physical sciences ,Quasiparticle ,Beta (velocity) ,Atomic physics ,010306 general physics ,Intensity (heat transfer) - Abstract
The $\ensuremath{\beta}$ decays of $^{103,104m}\mathrm{Nb}$ were studied with the Summing NaI(Tl) (SuN) detector at the National Superconducting Cyclotron Laboratory. The $\ensuremath{\beta}$-decay feeding intensity distribution ${I}_{\ensuremath{\beta}}(E)$ for each isotope was extracted by measuring $\ensuremath{\gamma}$ rays in coincidence with an emitted electron. The ${I}_{\ensuremath{\beta}}(E)$ was extracted via the total absorption spectroscopy technique. The ${I}_{\ensuremath{\beta}}(E)$ for each nucleus was compared to predictions made by the quasiparticle random-phase approximation (QRPA) model which is commonly used to calculate $\ensuremath{\beta}$-decay properties for astrophysical applications. The main goal was to provide experimental data for neutron-rich nuclei, relevant to the astrophysical $r$ process. In addition, the extracted $\ensuremath{\beta}$-decay feeding intensity distributions can lead to a better understanding of nuclear structure in a region of rapid structure changes around $A=100$. Finally, experimental data for $^{104m}\mathrm{Nb}$ are also of interest to antineutrino studies of nuclear reactors.
- Published
- 2021
3. Total absorption spectroscopy of the β decay of Zr101,102 and Tc109
- Author
-
D.P. Scriven, A. Palmisano, Tomislav Marketin, J. Gombas, Peter Möller, Sean Liddick, Paul DeYoung, A. Spyrou, Alejandro Algora, Alexander Dombos, C. J. Prokop, F. Naqvi, S. J. Quinn, T. N. Ginter, Anna Simon, J. Brett, Mallory Smith, Thomas Baumann, Benjamin P. Crider, J. Pereira, Stephanie Lyons, Pedro Sarriguren, S. Valenta, and W.-J. Ong
- Subjects
Physics ,Total absorption spectroscopy ,010308 nuclear & particles physics ,Neutron emission ,Nuclear Theory ,Type (model theory) ,01 natural sciences ,Superconducting cyclotron ,0103 physical sciences ,Quasiparticle ,Beta (velocity) ,Atomic physics ,010306 general physics ,Intensity (heat transfer) ,Beam (structure) - Abstract
The $\ensuremath{\beta}$ decay of $^{101,102}\mathrm{Zr}$ and $^{109}\mathrm{Tc}$ was studied using the technique of total absorption spectroscopy. The experiment was performed at the National Superconducting Cyclotron Laboratory using the Summing NaI(Tl) (SuN) detector in the first-ever application of total absorption spectroscopy with a fast beam produced via projectile fragmentation. The $\ensuremath{\beta}$-decay feeding intensity and Gamow-Teller transition strength distributions were extracted for these three decays. The extracted distributions were compared to three different quasiparticle random-phase approximation (QRPA) models based on different mean-field potentials. A comparison with calculations from one of the QRPA models was performed to learn about the ground-state shape of the parent nucleus. For $^{101}\mathrm{Zr}$ and $^{102}\mathrm{Zr}$, calculations assuming a pure shape configuration (oblate or prolate) were not able to reproduce the extracted distributions. These results may indicate that some type of mixture between oblate and prolate shapes is necessary to reproduce the extracted distributions. For $^{109}\mathrm{Tc}$, a comparison of the extracted distributions with QRPA calculations suggests a dominant oblate configuration. The other two QRPA models are commonly used to provide $\ensuremath{\beta}$-decay properties in $r$-process network calculations. This work shows the importance of making comparisons between the experimental and theoretical $\ensuremath{\beta}$-decay distributions, rather than just half-lives and $\ensuremath{\beta}$-delayed neutron emission probabilities, as close to the $r$-process path as possible.
- Published
- 2021
4. Isovector excitations in 100Nb and their decays by neutron emission studied via the Mo100(t,He3+n) reaction at 115 MeV/u
- Author
-
B. A. Brown, R. G. T. Zegers, S. Lipschutz, W.-J. Ong, E. Kwan, W. A. Peters, A. Spyrou, C. Robin, Alexander Dombos, J. Pereira, M.N. Harakeh, M. Scott, Sean Liddick, Robert Grzywacz, M. Madurga, D. Bazin, G. Perdikakis, K. Miki, Sam M. Austin, C. Sullivan, Elena Litvinova, R. Titus, M. T. Mustonen, and S. V. Paulauskas
- Subjects
Physics ,Nuclear and High Energy Physics ,Isovector ,010308 nuclear & particles physics ,Branching fraction ,Neutron emission ,Nuclear Theory ,Resonance ,01 natural sciences ,Spectral line ,Nuclear physics ,Excited state ,0103 physical sciences ,Atomic physics ,Nuclear Experiment ,010306 general physics ,Multipole expansion ,Excitation - Abstract
Spin–isospin excitations in Nb 100 were studied via the Mo 100 ( t , He 3 ) charge-exchange reaction at 115 MeV/u with the goal to constrain theoretical models used to describe the isovector spin response of nuclei. The experiment was performed with a secondary beam of tritons, and 3He particles were analyzed in the S800 magnetic spectrometer. Decay by neutron emission from excited states in Nb 100 was observed by using plastic and liquid scintillator arrays. Differential cross sections were analyzed and monopole excitations were revealed by using a multipole decomposition analysis. The Gamow–Teller transition strength observed at low excitation energies, which is important for estimating the electron-capture rate in astrophysical scenarios, was strongly fragmented and reduced compared to single-particle and spherical mean-field models. The consideration of deformation in the theoretical estimates was found to be important to better describe the fragmentation and strengths. A strong excitation of the isovector spin giant monopole resonance was observed, and well reproduced by the mean-field models. Its presence makes the extraction of Gamow–Teller strengths at high excitation energies difficult. The branches for statistical and direct decay by neutron emission were identified in the spectra. The upper limit for the branching ratio by direct decay (integrated over all observed excitations) was determined to be 20 ± 6 % . Even though the statistical uncertainties in the neutron-coincident data were too large to perform detailed studies of the decay by neutron emission from individual states and resonances, the experiment demonstrates the feasibility of the method.
- Published
- 2017
5. Experimental constraints on the Zn73(n,γ)Zn74 reaction rate
- Author
-
Sunniva Siem, Benjamin P. Crider, Therese Renstrøm, Sean Liddick, Alexander Dombos, A. Spyrou, G. Perdikakis, L. Crespo Campo, C. J. Prokop, S. J. Quinn, F. Naqvi, Shea Mosby, Aaron Couture, R. Lewis, A. C. Larsen, D. L. Bleuel, and Magne Guttormsen
- Subjects
Physics ,Total absorption spectroscopy ,010308 nuclear & particles physics ,Astrophysics::High Energy Astrophysical Phenomena ,Strength function ,01 natural sciences ,Reaction rate ,Superconducting cyclotron ,0103 physical sciences ,Neutron ,Production (computer science) ,Atomic physics ,Nuclear Experiment ,010306 general physics - Abstract
Background: The recent observation of a neutron-star merger finally confirmed one astrophysical location of the rapid neutron-capture process (r-process). Evidence of the production of $Al140$ nuclei was seen, but there is still little detailed information about how those lighter elements are produced in such an environment. Many of the questions surrounding the $A\ensuremath{\approx}80$ nuclei are likely to be answered only when the nuclear physics involved in the production of r-process nuclei is well understood. Neutron-capture reactions are an important component of the r-process, and neutron-capture cross sections of r-process nuclei, which are very neutron rich, have large uncertainties.Purpose: Indirectly determine the neutron-capture cross section and reaction rate of $^{73}\mathrm{Zn}(n,\ensuremath{\gamma})^{74}\mathrm{Zn}$.Methods: The nuclear level density (NLD) and $\ensuremath{\gamma}$-ray strength function ($\ensuremath{\gamma}\mathrm{SF}$) of $^{74}\mathrm{Zn}$ were determined following a total absorption spectroscopy (TAS) experiment focused on the $\ensuremath{\beta}$ decay of $^{74}\mathrm{Cu}$ into $^{74}\mathrm{Zn}$ performed at the National Superconducting Cyclotron Laboratory. The NLD and $\ensuremath{\gamma}\mathrm{SF}$ were used as inputs in a Hauser-Feshbach statistical model to calculate the neutron-capture cross section and reaction rate.Results: The NLD and $\ensuremath{\gamma}\mathrm{SF}$ of $^{74}\mathrm{Zn}$ were experimentally constrained for the first time using $\ensuremath{\beta}$-delayed $\ensuremath{\gamma}$ rays measured with TAS and the $\ensuremath{\beta}$-Oslo method. The NLD and $\ensuremath{\gamma}\mathrm{SF}$ were then used to constrain the neutron-capture cross section and reaction rate for the $^{73}\mathrm{Zn}(n,\ensuremath{\gamma})^{74}\mathrm{Zn}$ reaction.Conclusions: The uncertainty in the neutron-capture cross section and reaction rate of $^{73}\mathrm{Zn}(n,\ensuremath{\gamma})^{74}\mathrm{Zn}$ calculated in TALYS was reduced to under a factor of 2 from a factor of 5 in the cross section and a factor of 11 in the reaction rate using the experimentally obtained NLD and $\ensuremath{\gamma}\mathrm{SF}$.
- Published
- 2019
6. Enhanced low-energy γ-decay strength of Ni70 and its robustness within the shell model
- Author
-
Sunniva Siem, J. E. Midtbø, A. C. Larsen, A. Spyrou, F. Naqvi, G. Perdikakis, L. Crespo Campo, Alexander Dombos, Shea Mosby, Therese Renstrøm, R. Lewis, Aaron Couture, Sergei Kamerdzhiev, Benjamin P. Crider, S. Karampagia, Sean Liddick, Magne Guttormsen, D. L. Bleuel, O. Achakovskiy, S. J. Quinn, C. J. Prokop, and B. A. Brown
- Subjects
Physics ,010308 nuclear & particles physics ,Astrophysics::High Energy Astrophysical Phenomena ,Nuclear Theory ,SHELL model ,Space (mathematics) ,01 natural sciences ,Low energy ,Nucleosynthesis ,0103 physical sciences ,Quasiparticle ,Radiative transfer ,Atomic physics ,Nuclear Experiment ,010306 general physics ,Nuclear theory - Abstract
Neutron-capture reactions on very neutron-rich nuclei are essential for heavy-element nucleosynthesis through the rapid neutron-capture process, now shown to take place in neutron-star merger events. For these exotic nuclei, radiative neutron capture is extremely sensitive to their $\ensuremath{\gamma}$-emission probability at very low $\ensuremath{\gamma}$ energies. In this work, we present measurements of the $\ensuremath{\gamma}\text{-decay}$ strength of $^{70}\mathrm{Ni}$ over the wide range $1.3\ensuremath{\le}{E}_{\ensuremath{\gamma}}\ensuremath{\le}8$ MeV. A significant enhancement is found in the $\ensuremath{\gamma}\text{-decay}$ strength for transitions with ${E}_{\ensuremath{\gamma}}l3$ MeV. At present, this is the most neutron-rich nucleus displaying this feature, proving that this phenomenon is not restricted to stable nuclei. We have performed $E1$-strength calculations within the quasiparticle time-blocking approximation, which describe our data above ${E}_{\ensuremath{\gamma}}\ensuremath{\simeq}5$ MeV very well. Moreover, large-scale shell-model calculations indicate an $M1$ nature of the low-energy $\ensuremath{\gamma}$ strength. This turns out to be remarkably robust with respect to the choice of interaction, truncation, and model space, and we predict its presence in the whole isotopic chain, in particular the neutron-rich $^{72,74,76}\mathrm{Ni}$.
- Published
- 2018
7. Neutron-capture rates for explosive nucleosynthesis: the case of 68 Ni( n , γ ) 69 Ni
- Author
-
G. Perdikakis, Rebecca Lewis, D. L. Bleuel, Sunniva Siem, F. Naqvi, C. J. Prokop, Therese Renstrøm, S. J. Quinn, L. Crespo Campo, Ann-Cecilie Larsen, Magne Guttormsen, Aaron Couture, Alexander Dombos, A. Spyrou, Sean Liddick, Matthew Mumpower, Benjamin P. Crider, Shea Mosby, and Rebecca Surman
- Subjects
Nuclear reaction ,Physics ,Nuclear and High Energy Physics ,010308 nuclear & particles physics ,01 natural sciences ,7. Clean energy ,Nuclear physics ,Reaction rate ,Neutron capture ,Nucleosynthesis ,Excited state ,0103 physical sciences ,Nuclear astrophysics ,r-process ,Atomic physics ,010306 general physics ,Radioactive decay - Abstract
Neutron-capture reactions play an important role in heavy element nucleosynthesis, since they are the driving force for the two processes that create the vast majority of the heavy elements. When a neutron capture occurs on a short-lived nucleus, it is extremely challenging to study the reaction directly and therefore the use of indirect techniques is essential. The present work reports on such an indirect measurement that provides strong constraints on the 68Ni(n, γ)69Ni reaction rate. This is done by populating the compound nucleus 69Ni via the β decay of 69Co and measuring the γ-ray deexcitation of excited states in 69Ni. The β-Oslo method was used to extract the γ-ray strength function and the nuclear level density. In addition the half-life of 69Co was extracted and found to be in agreement with previous literature values. Before the present results, the 68Ni(n, γ)69Ni reaction was unconstrained and the purely theoretical reaction rate was highly uncertain. The new uncertainty on the reaction rate based on the present experiment (variation between upper and lower limit) is approximately a factor of 3. The commonly used reaction libraries JINA-REACLIB and BRUSLIB are in relatively good agreement with the experimental rate. The impact of the new rate on weak r-process calculations is discussed. This research was first published in Journal of Physics G: Nuclear and Particle Physics. © IOP Publishing.
- Published
- 2017
- Full Text
- View/download PDF
8. Total absorption spectroscopy of theβdecay ofGa76
- Author
-
Amanda Gehring, F. Naqvi, Chandana Sumithrarachchi, David J. Morrissey, Remco Zegers, S. J. Quinn, B. A. Brown, Sean Liddick, Dong-Liang Fang, K. Cooper, A. Spyrou, Alexander Dombos, and Anna Simon
- Subjects
Physics ,Superconducting cyclotron ,Transition strength ,Total absorption spectroscopy ,010308 nuclear & particles physics ,0103 physical sciences ,High Energy Physics::Experiment ,Beta (velocity) ,Atomic physics ,010306 general physics ,01 natural sciences ,Intensity (heat transfer) - Abstract
The $\ensuremath{\beta}$ decay of $^{76}\mathrm{Ga}$ was studied using the technique of total absorption spectroscopy for the first time. The experiment was performed at the National Superconducting Cyclotron Laboratory using the Summing NaI(Tl) detector. The extracted $\ensuremath{\beta}$-decay feeding intensity distribution and Gamow-Teller transition strength distribution are compared to shell-model calculations to help constrain nuclear matrix elements relevant to the neutrinoless double-$\ensuremath{\beta}$ decay of $^{76}\mathrm{Ge}$.
- Published
- 2016
9. Shape coexistence from lifetime and branching-ratio measurements in 68,70Ni
- Author
-
S. Suchyta, S. J. Quinn, C. J. Prokop, T. Lauritsen, Robert Grzywacz, J. L. Harker, N. Larson, Mohammad Alshudifat, Benjamin P. Crider, J. J. Carroll, S. Zhu, A. Spyrou, C. J. Chiara, Sean Liddick, Alexander Dombos, A. D. Ayangeakaa, Jun Chen, F. Recchia, W. B. Walters, Rebecca Lewis, M. P. Carpenter, R. V. F. Janssens, H. M. David, and Shintaro Go
- Subjects
Physics ,Nuclear and High Energy Physics ,Proton ,010308 nuclear & particles physics ,Branching fraction ,Nuclear Theory ,Molecular ,01 natural sciences ,Atomic ,Nuclear & Particles Physics ,lcsh:QC1-999 ,Particle and Plasma Physics ,Affordable and Clean Energy ,0103 physical sciences ,Neutron ,Nuclear ,Atomic physics ,010306 general physics ,Wave function ,lcsh:Physics ,Excitation ,Mathematical Physics ,Astronomical and Space Sciences - Abstract
Author(s): Crider, BP; Prokop, CJ; Liddick, SN; Al-Shudifat, M; Ayangeakaa, AD; Carpenter, MP; Carroll, JJ; Chen, J; Chiara, CJ; David, HM; Dombos, AC; Go, S; Grzywacz, R; Harker, J; Janssens, RVF; Larson, N; Lauritsen, T; Lewis, R; Quinn, SJ; Recchia, F; Spyrou, A; Suchyta, S; Walters, WB; Zhu, S | Abstract: Shape coexistence near closed-shell nuclei, whereby states associated with deformed shapes appear at relatively low excitation energy alongside spherical ones, is indicative of the rapid change in structure that can occur with the addition or removal of a few protons or neutrons. Near 68Ni (Z=28, N=40), the identification of shape coexistence hinges on hitherto undetermined transition rates to and from low-energy 0+ states. In 68,70Ni, new lifetimes and branching ratios have been measured. These data enable quantitative descriptions of the 0+ states through the deduced transition rates and serve as sensitive probes for characterizing their nuclear wave functions. The results are compared to, and consistent with, large-scale shell-model calculations which predict shape coexistence. With the firm identification of this phenomenon near 68Ni, shape coexistence is now observed in all currently accessible regions of the nuclear chart with closed proton shells and mid-shell neutrons.
- Published
- 2016
10. New low-energy0+state and shape coexistence inNi70
- Author
-
S. Suchyta, J. L. Harker, S. J. Quinn, N. Larson, C. J. Prokop, D. Seweryniak, T. Lauritsen, Sean Liddick, Benjamin P. Crider, M. P. Carpenter, A. D. Ayangeakaa, S. Zhu, A. Spyrou, Shintaro Go, J. J. Carroll, Alexander Dombos, Rebecca Lewis, Jun Chen, R. V. F. Janssens, F. Recchia, C. J. Chiara, H. M. David, and W. B. Walters
- Subjects
Physics ,Nuclear and High Energy Physics ,Proton ,Double beta decay ,Excited state ,Magnetic monopole ,Neutron ,Atomic physics ,Space (mathematics) ,Spectroscopy ,Energy (signal processing) - Abstract
In recent models, the neutron-rich Ni isotopes around $N=40$ are predicted to exhibit multiple low-energy excited ${0}^{+}$ states attributed to neutron and proton excitations across both the $N=40$ and $Z=28$ shell gaps. In $^{68}\mathrm{Ni}$, the three observed ${0}^{+}$ states have been interpreted in terms of triple shape coexistence between spherical, oblate, and prolate deformed shapes. In the present work a new $({0}_{2}^{+})$ state at an energy of 1567 keV has been discovered in $^{70}\mathrm{Ni}$ by using $\ensuremath{\beta}$-delayed, $\ensuremath{\gamma}$-ray spectroscopy following the decay of $^{70}\mathrm{Co}$. The precipitous drop in the energy of the prolate-deformed ${0}^{+}$ level between $^{68}\mathrm{Ni}$ and $^{70}\mathrm{Ni}$ with the addition of two neutrons compares favorably with results of Monte Carlo shell-model calculations carried out in the large $fp{g}_{9/2}{d}_{5/2}$ model space, which predict a ${0}_{2}^{+}$ state at 1525 keV in $^{70}\mathrm{Ni}$. The result extends the shape-coexistence picture in the region to $^{70}\mathrm{Ni}$ and confirms the importance of the role of the tensor component of the monopole interaction in describing the structure of neutron-rich nuclei.
- Published
- 2015
11. (α,γ)cross section measurements in the region of lightpnuclei
- Author
-
Q. Li, M. Moran, S. J. Quinn, B. Bucher, Joachim Görres, A. Spyrou, Manoel Couder, Paul DeYoung, A. Battaglia, Wanpeng Tan, N. Paul, Anna Simon, J. Pereira, Mallory Smith, Rashi Talwar, Alexander Dombos, A. Long, C. Casarella, Karl Smith, M. Bowers, Michael Wiescher, Antonios Kontos, D. Robertson, and E. Stech
- Subjects
Nuclear reaction ,Physics ,Nuclear and High Energy Physics ,Potential impact ,Cross section (physics) ,Scattering ,Radiative capture ,Production (computer science) ,Sensitivity (control systems) ,p-Nuclei ,Atomic physics - Abstract
The $^{90}\mathrm{Zr}(\ensuremath{\alpha},\ensuremath{\gamma})^{94}\mathrm{Mo},\phantom{\rule{0.16em}{0ex}}^{92}\mathrm{Zr}(\ensuremath{\alpha},\ensuremath{\gamma})^{96}\mathrm{Mo}$, and $^{74}\mathrm{Ge}(\ensuremath{\alpha},\ensuremath{\gamma})^{78}\mathrm{Se}$ reaction cross sections were measured for the first time in an effort to expand the existing experimental database for $(\ensuremath{\alpha},\ensuremath{\gamma})$ reactions relevant for the production of $p$ nuclei in the universe. In particular, the $^{90}\mathrm{Zr}(\ensuremath{\alpha},\ensuremath{\gamma})^{94}\mathrm{Mo}$ reaction was identified by a sensitivity study for its potential impact on the $\ensuremath{\gamma}$-process mass flow in the region of light $p$ nuclei. The measurements were performed for energies ${E}_{\ensuremath{\alpha}}=9.5--12.0$ MeV at the University of Notre Dame using the SuN detector and the $\ensuremath{\gamma}$-summing technique. The results are compared to theoretical calculations from the talys and non-smoker nuclear reaction codes, and it is shown that the data greatly reduce the uncertainty in the cross section for the measured energies. The talys parameters that provide the best description of the experimental data are reported.
- Published
- 2015
12. Systematic study of(α,γ)reactions for stable nickel isotopes
- Author
-
N. Paul, A. Long, Karl Smith, Manoel Couder, Rashi Talwar, Alexander Dombos, Antonios Kontos, Wanpeng Tan, M. Beard, S. J. Quinn, A. Spyrou, B. Bucher, Joachim Görres, Michael Wiescher, M. Moran, Anna Simon, Paul DeYoung, D. Robertson, E. Stech, and J. Pereira
- Subjects
Physics ,Nuclear and High Energy Physics ,Range (particle radiation) ,Isotope ,Radiative capture ,chemistry.chemical_element ,Reaction rate ,Systematic measurement ,Nickel ,Cross section (physics) ,chemistry ,Atomic physics ,Nuclear Experiment ,Energy (signal processing) - Abstract
A systematic measurement of the $(\ensuremath{\alpha},\ensuremath{\gamma})$ reaction for all the stable nickel isotopes has been performed using the $\ensuremath{\gamma}$-summing technique. For two of the isotopes, $^{60}\mathrm{Ni}$ and $^{61}\mathrm{Ni}$, the $\ensuremath{\alpha}$-capture cross sections have been experimentally measured for the first time. For $^{58,62,64}\mathrm{Ni}$, the current measurement is in excellent agreement with earlier results found in the literature, and additionally extends the energy range of the measured cross sections up to 8.7 MeV. The data provided a tool for testing the cross section predictions of Hauser-Feshbach calculations. The experimental results were compared to the cross sections calculated with the talys 1.6 code and commonly used databases non-smoker and bruslib. For each of the investigated isotopes a combination of input parameter for talys was identified that best reproduces the experimental data, and recommended reaction rate has been calculated. Additionally, a set of inputs for Hauser-Feshbach calculations was given that, simultaneously for all the isotopes under consideration, reproduces the experimental data within the experimental uncertainties.
- Published
- 2015
13. Novel technique for Constrainingr-Process (n,γ) Reaction Rates
- Author
-
K. Cooper, J. A. Rodriguez, G. Perdikakis, Magne Guttormsen, Remco Zegers, S. J. Quinn, F. Naqvi, Therese Renstrøm, Sean Liddick, A. Spyrou, David J. Morrissey, Anna Simon, Chandana Sumithrarachchi, Ann-Cecilie Larsen, and Alexander Dombos
- Subjects
Physics ,Novel technique ,010308 nuclear & particles physics ,Astrophysics::High Energy Astrophysical Phenomena ,Strength function ,General Physics and Astronomy ,7. Clean energy ,01 natural sciences ,Spectral line ,Nuclear physics ,Reaction rate ,Superconducting cyclotron ,0103 physical sciences ,r-process ,Atomic physics ,Nuclear Experiment ,010306 general physics - Abstract
A novel technique has been developed, which will open exciting new opportunities for studying the very neutron-rich nuclei involved in the $r$ process. As a proof of principle, the $\ensuremath{\gamma}$ spectra from the $\ensuremath{\beta}$ decay of $^{76}\mathrm{Ga}$ have been measured with the SuN detector at the National Superconducting Cyclotron Laboratory. The nuclear level density and $\ensuremath{\gamma}$-ray strength function are extracted and used as input to Hauser-Feshbach calculations. The present technique is shown to strongly constrain the $^{75}\mathrm{Ge}(n,\ensuremath{\gamma})^{76}\mathrm{Ge}$ cross section and reaction rate.
- Published
- 2014
14. Measurement of the90,92Zr(p,γ)91,93Nb reactions for the nucleosynthesis of elements nearA=90
- Author
-
Thomas Rauscher, Joachim Görres, Edward Stech, Bradley S. Meyer, B. Bucher, Karl Smith, A. Spyrou, Manoel Couder, A. Long, L. Y. Lin, Alexander Dombos, Anna Simon, S. J. Quinn, Xiao Fang, A. Kontos, Paul DeYoung, B. Stefanek, Daniel Robertson, A. Best, Amy Roberts, Michael Wiescher, Q. Li, Stephanie Lyons, X. D. Tang, A. Battaglia, Wanpeng Tan, and Mallory Smith
- Subjects
Physics ,Nuclear reaction ,Nuclear and High Energy Physics ,010308 nuclear & particles physics ,Radiative capture ,7. Clean energy ,01 natural sciences ,Nuclear physics ,Superconducting cyclotron ,Nucleosynthesis ,0103 physical sciences ,Sensitivity (control systems) ,Atomic physics ,010306 general physics - Abstract
Cross section measurements of the reactions ${}^{90,92}$Zr($p$,$\ensuremath{\gamma}$)${}^{91,93}$Nb were performed using the National Superconducting Cyclotron Laboratory Summing NaI(Tl) detector at the University of Notre Dame. These reactions are part of the nuclear reaction flow for the synthesis of the light $p$ nuclei. For the ${}^{90}$Zr($p$,$\ensuremath{\gamma}$)${}^{91}$Nb reaction the new measurement resolves the disagreement between previous results. For the ${}^{92}$Zr($p$,$\ensuremath{\gamma}$)${}^{93}$Nb reaction the present work reports the first measurement of this reaction cross section. Both reaction cross sections are compared to theoretical calculations and a very good agreement with the standard non-smoker model is observed.
- Published
- 2013
15. Probing the production mechanism of the lightp-process nuclei
- Author
-
Bradley S. Meyer, Manoel Couder, Paul DeYoung, Antonios Kontos, Q. Li, X. D. Tang, X. Fang, Graham F. Peaslee, Mallory Smith, Joachim Görres, A. Spyrou, S. J. Quinn, A. Battaglia, D. Robertson, E. Stech, Anna Simon, Alexander Dombos, Karl Smith, Wanpeng Tan, Stephanie Lyons, and Michael Wiescher
- Subjects
Nuclear reaction ,Nuclear physics ,Physics ,Reaction rate ,Nuclear and High Energy Physics ,Nucleosynthesis ,Production (computer science) ,Atomic physics ,Type II supernova ,Fermi gas ,Energy (signal processing) ,p-process - Abstract
In an effort to investigate the production of ${}^{74}$Se in $p$-process nucleosynthesis, the ${}^{74}$Ge($p$,$\ensuremath{\gamma}$)${}^{75}$As reaction cross section was measured in the relevant energy range of ${E}_{p}=1.6$--4.2 MeV. The measurements were carried out using the NSCL SuN detector at the University of Notre Dame. The results are in good agreement with previous work, extending the measurements to both lower and higher energies. The measurements are compared to theoretical predictions using the non-smoker and talys nuclear reaction codes. New and improved reaction rates are offered, and these reaction rates are used in a 25M${}_{\ensuremath{\bigodot}}$ Type II Supernova model to study their impact on the production of ${}^{74}$Se.
- Published
- 2013
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.