High-precision<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mi>p</mml:mi><mml:mo>,</mml:mo><mml:mi>t</mml:mi><mml:mo stretchy="false">)</mml:mo></mml:mrow></mml:math>reaction measurement to determine<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mmultiscripts><mml:mi mathvariant="normal">Ne</mml:mi><mml:mprescripts /><mml:none /><mml:mrow><mml:mn>18</mml:mn></mml:mrow></mml:mmultiscripts><mml:mrow>

Matić, A.; Berg, A.M van der; Harakeh, Mohsen; Wörtche, H. J.; Berg, G.P.A.; Couder, M.; Fisker, J. L.; Görres, J.; LeBlanc, P. J.; O’Brien, S.; Wiescher, M.; Fujita, K.; Hatanaka, K.; Sakemi, Y.; Shimizu, Y.; Tameshige, Y.; Tamii, A.; Yosoi, M.; Adachi, T.; Fujita, Y.; Shimbara, Y.; Fujita, H.; Wakasa, T.; Hess, Peter O.; Brown, B. A.; Schatz, H.

doi:10.1103/physrevc.80.055804

Cited by 43 publications

(45 citation statements)

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“…However, a comparison with the rate from the direct measurement of Groombridge et al [4] reveals significant discrep- ancies both in energy dependence and magnitude, with a disagreement of up to a factor of ≃ 25 at T=2.4GK. Our rate is also between a factor of about 10-40 lower than the rate deduced using an indirect approach by Matić et al [9] for 0.9 GK≤T≤2.4 GK. It should be pointed out that such discrepancies would persist (albeit to a lesser extent) even by allowing for inelastic contributions to our rate because, according to HF predictions, these latter would increase our rate by at most a factor of ∼3 (see Fig.…”

Section: The Astrophysicalcontrasting

confidence: 38%

“…Theoretical predictions based on Hauser-Feshbach formalism are also shown for comparison (red lines). The total stellar rates from [4] (black dotted line) and [9] (blue dash-dotted line) are larger than the present rate by up to a factor of 25 and 40, respectively, at T=2.4GK. This temperature is chosen as an example to illustrate quantitative differences between the various rates.…”

Section: Fig 3 (Colour Online) Astrophysicalmentioning

confidence: 99%

“…The origin of these large discrepancies is not clear but we note that the resonance widths used in [4,18] imply unphysically large alpha-decay partial widths. Similarly, the rate in [9] is subject to large uncertainties in the choice of resonance strength values, which are not determined experimentally. Outside of the temperature range shown in Figure 3 our rate can be extrapolated but its reliability decreases drastically, especially for T ≤ 0.95 GK and thus a direct comparison with the rate of [6] is not possible.…”

Section: The Astrophysicalmentioning

confidence: 99%

mentioning

confidence: 99%

“…Inspection of the structure of the mirror nucleus 21 Na reaction rate [9]. Yet, a comparison of all the reaction rates currently available shows discrepancies of up to several orders of magnitude both below and above T ∼1GK (see [9] and references therein). In addition, it remains unclear whether the Hauser-Feshbach statistical calculations provide a reliable estimate of the 18 Ne(α,p) 21 Na rate in the whole temperature region relevant to nucleosynthesis in X-ray bursts.…”

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confidence: 99%

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Measurement of theNe18(α,p0)Na21Reaction Cross Section in the

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The18 Ne(α,p) 21 Na reaction provides one of the main HCNO-breakout routes into the rp-process in X-ray bursts. The 18 Ne(α,p0) 21 Na reaction cross section has been determined for the first time in the Gamow energy region for peak temperatures T∼2GK by measuring its time-reversal reaction 21 Na(p,α) 18 Ne in inverse kinematics. The astrophysical rate for ground-state to ground-state transitions was found to be a factor of 2 lower than Hauser-Feshbach theoretical predictions. Our reduced rate will affect the physical conditions under which breakout from the HCNO cycles occurs via the 18 Ne(α,p) 21 Na reaction.PACS numbers: 25.60. 26.30.Ca, 25.45.Hi Type I X-ray bursters (XRBs) exhibit brief recurrent bursts of intense X-ray emission and represent a frequent phenomenon in our Galaxy. Recent observations from space-borne X-ray satellites (BeppoSAX, RXTE, Chandra and XMM Newton) have provided a great wealth of data and have marked a new era in X-ray astronomy. Yet, to fully exploit these observations, similar advances in our understanding of the nuclear reactions responsible for the bursts are required. XRBs are driven by a thermonuclear runaway on the surface of a neutron star that accretes H-and He-rich material from a less evolved companion in a semi-detached binary system [1]. Depending on the mass accretion rate, high enough temperatures and densities can be achieved that trigger hydrogen burning through the hot, β-limited CNO cycles (HCNO) and the subsequent ignition of the triple-α process. However, the thermonuclear runaway requires a breakout from the HCNO cycle and the ignition of the rapid-proton capture process (rp-process) at peak temperatures T≃ 1-2 GK. The 18 Ne(α,p) 21 Na reaction is believed to provide the main breakout route at T≥0.8GK and ρ ≥10 5 g/cm 3 [2], but the actual physical conditions at which the breakout occurs depend critically on the accurate knowledge of the 18 Ne(α,p) 21 Na reaction rate. A direct investigation of this important reaction is severely hampered by the low intensity (≤ 10 6 pps) of radioactive 18 Ne beams presently available and by the further complications associated with the use of a 4 He gas target. Thus, the only two direct measurements available to date extend to minimum energies of E cm = 2.0 MeV [3] and E cm = 1.7 MeV [4]. These are still too high compared to the energy region E cm ≤1.5 MeV of interest for HCNO breakout in X-ray bursts.The first theoretical estimates of the 18 Ne(α,p) 21 Na reaction rate [5] were based on sparse experimental information on the level structure of the compound nucleus 22 Mg above the α-particle threshold at 8.14 MeV. Inspection of the structure of the mirror nucleus . Yet, a comparison of all the reaction rates currently available shows discrepancies of up to several orders of magnitude both below and above T ∼1GK (see [9] and references therein). In addition, it remains unclear whether the Hauser-Feshbach statistical calculations provide a reliable estimate of the 18 Ne(α,p) 21 Na rate in the whole temperature region relevant ...

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Section: The Astrophysicalcontrasting

confidence: 38%

Section: Fig 3 (Colour Online) Astrophysicalmentioning

confidence: 99%