Preparation of 20Ne, 24Mg, 28Si, 32S, and 36Ar targets by ion implantation into thin carbon foils

Wrede, C.; Deryckx, Kseniya S.; Freeman, B. M.; Garcı́a, A.; Harper, G.; Palmer, A.S.C.; Short, D.; Will, D. I.

doi:10.1016/j.nimb.2010.09.009

Cited by 8 publications

(5 citation statements)

References 9 publications

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“…The MP tandem Van de Graaf was used to accelerate a 300-700 nA 2 H 1+ beam to an energy of 22 MeV [23]. 36 Ar targets were produced at the Center for Experimental Nuclear Physics and Astrophysics (CENPA) by implanting 3-6 µg/cm 2 of 36 Ar ions into 30 µg/cm 2 natural abundance carbon foils, as described in [24][25][26]. The 36 Ar implantation beam purity was determined by comparing the beam current for components with mass numbers A = 36, 38, and 40 prior to mass selection and they were measured to be 19, 4, and 6000 nA, respectively.…”

Section: Methodsmentioning

confidence: 99%

Discovery of ³⁴^g^,^mCl(p, γ)³⁵Ar Resonances Relevant for Classical Nova Nucleosynthesis

Fry¹,

Wrede²,

Bishop³

et al. 2017

Proceedings of the 14th International Symposium on Nuclei in the Cosmos (NIC2016)

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Sulfur isotopic ratios have the potential to distinguish presolar grains of classical novae and type II supernovae origin. The current lack of experimentally determined 34g,m Cl(p, γ) 35 Ar reaction rates leads to large uncertainties in the production of 34 S in oxygen-neon classical nova models. As a first step toward determining these reaction rates, we have measured 35 Ar resonances up to 800 keV above the 35 Ar proton emission threshold. These resonances were populated using the 36 Ar(d, t) 35 Ar reaction, and the tritons were momentum analyzed by a high resolution quadrupole-dipole-dipole-dipole (Q3D) magnetic spectrograph. Seventeen new 35 Ar levels have been discovered, and uncertainties associated with the energies of the five previously known levels have been substantially reduced. Experimental level densities were then compared to calculated level densities, using the WBMB Hamiltonian within the sd − p f model space. This comparison indicates that most of the expected resonances in this region have been observed.

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Section: Methodsmentioning

confidence: 99%

Discovery of ³⁴^g^,^mCl(p, γ)³⁵Ar Resonances Relevant for Classical Nova Nucleosynthesis

Fry¹,

Wrede²,

Bishop³

et al. 2017

Proceedings of the 14th International Symposium on Nuclei in the Cosmos (NIC2016)

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Section: Methodsmentioning

confidence: 99%

Discovery of34g,mCl(p,γ)35Arresonances activated at classical nova temperatures

et al. 2015

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Background: The thermonuclear 34g,m Cl(p, γ) 35 Ar reaction rates are unknown due to a lack of experimental nuclear physics data. Uncertainties in these rates translate to uncertainties in 34 S production in models of classical novae on oxygen-neon white dwarfs.34 S abundances have the potential to aid in the classification of presolar grains.Purpose: Determine resonance energies for the 34g,m Cl(p, γ) 35 Ar reactions within the region of astrophyical interest for classical novae to a precision of a few keV as an essential first step toward constraining their thermonuclear reaction rates. Method:35 Ar excited states were populated by the 36 Ar(d, t) 35 Ar reaction at E(d)=22 MeV and reaction products were momentum analyzed by a high resolution quadrupole-dipole-dipole-dipole (Q3D) magnetic spectrograph. Results: Seventeen new35 Ar levels have been detected at a statistically significant level in the region Ex ≈ 5.9-6.7 MeV (Er < 800 keV) and their excitation energies have been determined to typical uncertainties of 3 keV. The uncertainties for five previously known levels have also been reduced substantially. The measured level density was compared to those calculated using the WBMB Hamiltonian within the sd − pf model space. Conclusions:Most of the resonances in the region of astrophyical interest have likely been discovered and their energies have been determined, but the resonance strengths are still unknown, and experimentally constraining the 34g,m Cl(p, γ) 35 Ar reaction rates will require further experiments.

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“…The two most recent measurements [4,9] produced values that differed from each other systematically in the region of astrophysical interest by about 4 keV. The earlier measurement [3,9,10] carried a combined statistical and systematic uncertainty of ≈ 0.5 keV. The latter measurement [4] carried statistical uncertainties of ≈ 2 keV and a systematic uncertainty of 4 keV.…”

Section: CL Excitation Energiesmentioning

confidence: 99%

“…[4] are systematically low and that the systematic effect increases in magnitude with increasing excitation energy (this increase may saturate). Such an increase could result from the fact that the lowest excitation energies were strongly influenced by internal 32 Cl calibration points and that the calibration gradually became more dependent on external calibration points towards higher energies [4], introducing substantial systematic uncertainties from the dependence on the assumed target properties [3,9,10] (primarily) and reaction Q values [9] (secondarily).…”

Section: CL Excitation Energiesmentioning

confidence: 99%

γ-ray constraints on the properties of unbound32Cl levels

et al. 2012

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Systematic differences between measurements of excitation energies and branching ratios of unbound 32 Cl levels near the proton threshold have recently emerged. We investigate these 32 Cl properties using independent information by analyzing existing 32 Ar(βγ) 32 Cl data and using published values from measurements of the 32 S( 3 He,tγ) 32 Cl reaction. Significant evidence emerges in support of particular values. The results increase the thermonuclear rate of the 31 S(p, γ) 32 Cl reaction by up to a factor of two over the temperature range of 0.4 to 2 GK that is reached during type I x-ray bursts on hydrogen-accreting neutron stars.

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Preparation of 20Ne, 24Mg, 28Si, 32S, and 36Ar targets by ion implantation into thin carbon foils

Cited by 8 publications

References 9 publications

Discovery of ³⁴^g^,^mCl(p, γ)³⁵Ar Resonances Relevant for Classical Nova Nucleosynthesis

Discovery of ³⁴^g^,^mCl(p, γ)³⁵Ar Resonances Relevant for Classical Nova Nucleosynthesis

Discovery of34g,mCl(p,γ)35Arresonances activated at classical nova temperatures

γ-ray constraints on the properties of unbound32Cl levels

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Preparation of 20Ne, 24Mg, 28Si, 32S, and 36Ar targets by ion implantation into thin carbon foils

Cited by 8 publications

References 9 publications

Discovery of 34g,mCl(p, γ)35Ar Resonances Relevant for Classical Nova Nucleosynthesis

Discovery of 34g,mCl(p, γ)35Ar Resonances Relevant for Classical Nova Nucleosynthesis

Discovery of34g,mCl(p,γ)35Arresonances activated at classical nova temperatures

γ-ray constraints on the properties of unbound32Cl levels

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Product

Resources

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Discovery of ³⁴^g^,^mCl(p, γ)³⁵Ar Resonances Relevant for Classical Nova Nucleosynthesis

Discovery of ³⁴^g^,^mCl(p, γ)³⁵Ar Resonances Relevant for Classical Nova Nucleosynthesis