Nuclear Data Sheets for A = 44

Chen, J.; Singh, Balraj; Cameron, J. A.

doi:10.1016/j.nds.2011.08.005

Cited by 87 publications

(80 citation statements)

References 475 publications

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“…The measured strength for the 1.84 MeV resonance in this work (0.28 ± 0.04) eV agrees well with the documented (0.28 ± 0.03) eV value [35]. Review of the strong resonance triplet gives a fit value of integrated resonance ωγ int = 9.0 ± 1.2 eV, showing good agreement to the literature value of 8.5 ± 1.1 eV [36] and previous measurements of 7.6 ± 1.0 eV [13] and 8.8 ± 3.0 eV [12]. The ωγ value for this triplet is reliably consistent for all scans made during target degradation monitoring, giving increased confidence in the procedure.…”

Section: A Excitation Functionsupporting

confidence: 91%

“…Figure 1 shows the reaction rates normalized to the PGS rate based on all of the previously accumulate prompt gamma work discussed above. The PGS rate used in the figure is tabulated by Chen et al [36], a detailed analysis was also provided by Rauscher et al 2000 [14]. In the astrophysically important region of a few 10 9 K, the reaction rate based the IKS studies is larger by a factor of 3 compared to the PGS rate, whereas the rate based on the AMS data shows a more significant enhancement by a factor of ∼ 3.75.…”

Section: Thementioning

confidence: 99%

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New measurement of the astrophysically important40Ca(α,γ)44Ti reaction

et al. 2012

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The relatively short-lived radionuclide 44 Ti is of considerable importance for the interpretation of nucleosynthesis in core collapse supernova environments. Production is predominantly through the 40 Ca(α,γ)44 Ti reaction, which has been studied in this work over the energy range Ecm = 2.73 -4.18 MeV, via direct γ counting and the 4π-summing technique, utilizing a previously characterized 12 inch × 12 inch single NaI crystal. The inferred reaction rate is compared here to both current experimental measurements and theoretical model calculations.

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Section: A Excitation Functionsupporting

confidence: 91%

Section: Thementioning

confidence: 99%

New measurement of the astrophysically important40Ca(α,γ)44Ti reaction

et al. 2012

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“…r = 2507 − 5259 keV are taken into account. In addition, 11 natural parity states between the α-particle threshold and the lowest-lying observed resonance can contribute to the total rate [46]. The compound nucleus 44 Ti exhibits a strong α-cluster structure, which was investigated in several works using α-particle transfer experiments.…”

Section: B Mean Proton Reduced Widthsmentioning

confidence: 99%

Mean proton andα-particle reduced widths of the Porter-Thomas distribution and astrophysical applications

et al. 2013

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The Porter-Thomas distribution is a key prediction of the Gaussian orthogonal ensemble in random matrix theory. It is routinely used to provide a measure for the number of levels that are missing in a given resonance analysis. The Porter-Thomas distribution is also of crucial importance for estimates of thermonuclear reaction rates where the contributions of certain unobserved resonances to the total reaction rate need to be taken into account. In order to estimate such contributions by randomly sampling over the Porter-Thomas distribution, the mean value of the reduced width must be known. We present mean reduced width values for protons and α-particles of compound nuclei in the A = 28 − 67 mass range. The values are extracted from charged-particle elastic scattering and reaction data that were measured at the Triangle Universities Nuclear Laboratory over several decades. Our new values differ significantly from those previously reported that were based on a preliminary analysis of a smaller data set. As an example for the application of our results, we present new thermonuclear rates for the 40 Ca(α,γ) 44 Ti reaction, which is important for 44 Ti production in core-collapse supernovae, and compare with previously reported results.

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“…The branching ratios of the 1157, 78.32, and 67.87 keV lines are 99.9%, 96.4%, and 93%, respectively (Chen et al 2011). 20 The present-day flux of photons produced in the radioactive decay of 44 Ti is therefore directly proportional to the initial synthesized mass of 44 Ti, independent of local conditions.…”

Section: Introductionmentioning

confidence: 98%

THE DISTRIBUTION OF RADIOACTIVE ⁴⁴Ti IN CASSIOPEIA A

Grefenstette

Fryer

Harrison

et al. 2016

ApJ

124

160

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The distribution of elements produced in the innermost layers of a supernova explosion is a key diagnostic for studying the collapse of massive stars. Here we present the results of a 2.4 Ms NuSTAR observing campaign aimed at studying the supernova remnant Cassiopeia A (Cas A). We perform spatially resolved spectroscopic analyses of the 44 Ti ejecta, which we use to determine the Doppler shift and thus the three-dimensional (3D) velocities of the 44 Ti ejecta. We find an initial 44 Ti mass of (1.54±0.21) ×10 −4 M e , which has a present-day average momentum direction of 340°±15°projected onto the plane of the sky (measured clockwise from celestial north) and is tilted by 58°±20°into the plane of the sky away from the observer, roughly opposite to the inferred direction of motion of the central compact object. We find some 44 Ti ejecta that are clearly interior to the reverse shock and some that are clearly exterior to it. Where we observe 44 Ti ejecta exterior to the reverse shock we also see shock-heated iron; however, there are regions where we see iron but do not observe 44 Ti. This suggests that the local conditions of the supernova shock during explosive nucleosynthesis varied enough to suppress the production of 44 Ti by at least a factor of two in some regions, even in regions that are assumed to be the result of processes like α-rich freezeout that should produce both iron and titanium.

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Nuclear Data Sheets for A = 44

Cited by 87 publications

References 475 publications

New measurement of the astrophysically important40Ca(α,γ)44Ti reaction

New measurement of the astrophysically important40Ca(α,γ)44Ti reaction

Mean proton andα-particle reduced widths of the Porter-Thomas distribution and astrophysical applications

THE DISTRIBUTION OF RADIOACTIVE ⁴⁴Ti IN CASSIOPEIA A

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Nuclear Data Sheets for A = 44

Cited by 87 publications

References 475 publications

New measurement of the astrophysically important40Ca(α,γ)44Ti reaction

New measurement of the astrophysically important40Ca(α,γ)44Ti reaction

Mean proton andα-particle reduced widths of the Porter-Thomas distribution and astrophysical applications

THE DISTRIBUTION OF RADIOACTIVE 44Ti IN CASSIOPEIA A

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THE DISTRIBUTION OF RADIOACTIVE ⁴⁴Ti IN CASSIOPEIA A