The<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mrow /><mml:mn>93</mml:mn></mml:msup></mml:math>Zr(<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>n</mml:mi><mml:mo>,</mml:mo><mml:mi>γ</mml:mi></mml:mrow></mml:math>) reaction up to 8 keV neutron energy

Tagliente, G.; Milazzo, Paolo; Fujii, K.; Abbondanno, U.; Aerts, G.; Álvarez, H.; Álvarez‐Velarde, F.; Andriamonje, S.; Andrzejewski, J.; Audouin, L.; Badurek, G.; Baumann, P.; Bečvář, F.; Belloni, F.; Berthoumieux, E.; Calviño, F.; Calviani, M.; Cano‐Ott, D.; Capote, R.; Carrapiço, C.; Cennini, P.; Chepel, V.; Chiaveri, E.; Colonna, N.; Cortés, G.; Couture, A.; Dahlfors, M.; David, S.; Dillmann, I.; Domingo‐Pardo, C.; Dridi, W.; Durán, I.; Eleftheriadis, C.; Embid‐Segura, M.; Ferrari, A.; Ferreira‐Marques, R.; Furman, W.; Gonçalves, I. F.; González‐Romero, E.; Gramegna, F.; Guerrero, C.; Gunsing, F.; Haas, Brian J.; Haight, R. C.; Heil, M.; Herrera-Martı́nez, A.; Jericha, E.; Käppeler, F.; Kadi, Y.; Karadimos, D.; Karamanis, D.; Kerveno, M.; Kossionides, E.; Krtička, M.; Lamboudis, C.; Leeb, H.; Lindote, A.; Lopes, I.; Lukić, S.; Marganiec, J.; Marrone, S.; Martínez, T.; Massimi, C.; Mastinu, P.; Mengoni, A.; Moreau, C.; Mosconi, M.; Neves, F.; Oberhummer, H.; O’Brien, S.; Papachristodoulou, C.; Papadopoulos, C.; Paradela, C.; Patronis, N.; Pavlik, A.; Pavlopoulos, P.; Perrot, L.; Pigni, Marco T.; Plag, R.; Plompen, A.; Plukis, A.; Poch, A.; Praena, J.; Pretel, C.; Quesada, J. M.; Reifarth, R.; Rosetti, M.; Rubbia, C.; Rudolf, G.; Rullhusen, P.; Salgado, J.; Santos, C.; Sarchiapone, L.; Savvidis, I.; Stéphan, C.; Taín, J. L.; Tassan‐Got, L.; Tavora, L.; Terlizzi, R.; Vannini, G.; Vaz, P.; Ventura, A.; Villamarı́n, D.; Vincente, M. C.; Vlachoudis, V.; Vlastou, R.; Voß, F.; Walter, S.; Wiescher, M.; Wisshak, K.

doi:10.1103/physrevc.87.014622

Cited by 41 publications

(15 citation statements)

References 33 publications

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“…The value log ω * -log(N (Zr)⁄N (Nb)) can thus be estimated using equation 14 and Extended Data Fig. 2, by fitting a straight line of slope 1 through the points for which the approximation fN s >> (1 -f)N 0 is valid.…”

Section: The 93 Zr -93 Nb Pair Used As a Thermometermentioning

confidence: 99%

“…The present determination of the s-process temperature relies on a single assumption, namely the equilibrium approximation along the Zr isotopic chain which is known to be valid locally 1 . For this reason, the uncertainties of the method are mainly those of the derived abundances and of the Zr experimental cross section 13,14 , i.e about 5% for the stable Zr isotopes and 11% for 93 Zr. Reducing the 93 Zr error would constrain even more the s-process operation temperature.…”

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confidence: 99%

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The temperature and chronology of heavy-element synthesis in low-mass stars

Neyskens¹,

Eck²,

Jorissen³

et al. 2015

Nature

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Roughly half of the elements heavier than iron in the Universe are believed to be synthesized in the late evolutionary stages of stars with masses between 0.8 and 8 solar masses. Deep inside the star, nuclei (mainly iron) capture neutrons and progressively build up ('s-process' 1, 2 ) heavier elements which are recurrently 'dredged-up' towards the stellar surface. Two neutron sources, activated at distinct temperatures, have been proposed: 13 C(α, n) 16 O or 22 Ne(α, n) 25 Mg. To explain measured stellar abundances 1-7 , stellar evolution models invoking the 13 C(α, n) 16 O neutron source which operates at temperatures of ~ 10 8 K are favored. However, isotopic ratios in primitive meteorites, reflecting nucleosynthesis in previous generations of stars, point at higher temperatures (above 3 × 10 8 K) 1 , requiring at least a late activation of 22 Ne(α, n) 25 Mg. Here we report on a determination of the s-process temperature directly in stars, using accurate zirconium and niobium abundances, independently of stellar evolution models. The derived temperature clearly supports 13 C(α,n) 16 O as the s-process neutron source. The radioactive pair 93 Zr -93 Nb used to estimate the s-process temperature also provides, together with the 99 Tc -99 Ru pair, chronometric information on the time elapsed since the start of the s-process (1-3 Myr).We obtained high-resolution spectra of 17 S stars and of 6 M stars with the high-resolution HERMES spectrograph 8 (λ⁄Δλ = 80 000, Extended Data Table 1 and Extended Data Fig. 1). S stars are s-process-enriched red giants with effective temperatures in the range 3000 to 4000 K, while M stars are similar giant stars but showing no s-process enhancement. Stellar parameters (effective temperature, surface gravity, carbon-to-oxygen ratio, s-process enhancement, and metallicity [Fe/H] = log 10 (N(Fe)⁄N(H)) star -log 10 (N(Fe)⁄N(H)) , where N(A) is the number density of element A and denotes the Sun), are determined by comparing observational data with predicted spectra and photometric colors 9 , computed from a grid of dedicated model atmospheres 10,11 . Fe, Zr, Nb and Tc abundances are derived, as well as the corresponding errors arising from estimated uncertainties on the stellar parameters (Extended Data Tables 2 -5 and Extended Data Fig. 2).Actually, S stars come in two varieties according to the presence or absence of Tc, a chemical element with no stable isotope. Extrinsic S stars lack Tc and are all binaries 12 . The atmosphere of these giant stars contains s-process material transferred from a companion that has completed its path through the asymptotic giant branch phase, and therefore reflects the entire s-process production history. We use the N(Nb)⁄N(Zr) ratio in these extrinsic S stars to derive the s-process temperature.Mono-isotopic Nb can only be produced by β-decay of 93 Zr. In extrinsic S stars, the time elapsed since the end of the mass transfer is much longer than the 93 Zr half-life (τ 1⁄2 = 1.53 Myr). Consequently, the N(Zr)⁄N(Nb) abundance measured today in the extrins...

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Section: The 93 Zr -93 Nb Pair Used As a Thermometermentioning

confidence: 99%

mentioning

confidence: 99%

The temperature and chronology of heavy-element synthesis in low-mass stars

Neyskens¹,

Eck²,

Jorissen³

et al. 2015

Nature

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“…6 of [7], which shows that gamma-rays from neutron capture in the walls of the experimental area represent the main background limitation in the relevant energy range for astrophysics, between 1 keV and 100 keV. To a large extent, this has been a constraint in recent (n,g) experiments, particularly those involving small amounts of -2 -radioactive samples [8] [9], a situation which has led to a limited astrophysical interpretation of the corresponding branching nuclei [10].…”

Section: Introductionmentioning

confidence: 99%

On the performance of large monolithic LaCl₃(Ce) crystals coupled to pixelated silicon photosensors

et al. 2018

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We investigate the performance of large area radiation detectors, with high energyand spatial-resolution, intended for the development of a Total Energy Detector with gamma-ray imaging capability, so-called i-TED. This new development aims for an enhancement in detection sensitivity in time-of-flight neutron capture measurements, versus the commonly used C 6 D 6 liquid scintillation total-energy detectors. In this work, we study in detail the impact of the readout photosensor on the energy response of large area (50´50 mm 2 ) monolithic LaCl 3 (Ce) crystals, in particular when replacing a conventional mono-cathode photomultiplier tube by an 8´8 pixelated silicon photomultiplier. Using the largest commercially available monolithic SiPM array (25 cm2), with a pixel size of 6´6 mm 2 , we have measured an average energy resolution of 3.92% FWHM at 662 keV for crystal thicknesses of 10, 20 and 30 mm. The results are confronted with detailed Monte Carlo (MC) calculations, where both optical processes and properties have been included for the reliable tracking of the scintillation photons. After the experimental validation of the MC model, se use our MC code to explore the impact of different a photosensor segmentation (pixel size and granularity) on the energy resolution. Our optical MC simulations predict only a marginal deterioration of the spectroscopic performance for pixels of 3´3 mm 2 .

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“…The production and destruction rates of 93 Zr is interesting for the interpretation of the relative abundance of the radioactive 93 Nb and 93 Zr pair, which can be used to estimate the s-process temperature and also, together with the 99 Tc-99 Ru pair, act as a chronometer to determine the time elapsed since the start of the s-process [9]. The 93 Zr(n,γ ) cross section has been measured up to 8 keV [10], but contributions to the Maxwellianaveraged cross section at higher energies are based on theoretical calculations and would benefit from experimental constraints [11].…”

Section: Introductionmentioning

confidence: 99%

Indirect $$(n, \gamma )^{91,92}$$ Zr Cross Section Measurements for the s-Process

Guttormsen

Goriely

Larsen

et al. 2019

Springer Proceedings in Physics

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Nuclear level densities (NLDs) and γ-ray strength functions (γ SFs) have been extracted from particle-γ coincidences of the 92 Zr(p,p γ) 92 Zr and 92 Zr(p,dγ) 91 Zr reactions using the Oslo method. The new 91,92 Zr γ SF data, combined with photonuclear cross sections, cover the whole energy range from E γ ≈ 1.5 MeV up to the giant dipole resonance at E γ ≈ 17 MeV. The wide-range γ SF data display structures at E γ ≈ 9.5 MeV, compatible with a superposition of the spin-flip M1 resonance and a pygmy E1 resonance. Furthermore, the γ SF shows a minimum at E γ ≈ 2-3 MeV and an increase at lower γ-ray energies. The experimentally constrained NLDs and γ SFs are shown to reproduce known (n,γ) and Maxwellian-averaged cross sections for 91,92 Zr using the TALYS reaction code, thus serving as a benchmark for this indirect method of estimating (n,γ) cross sections for Zr isotopes.

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The93Zr(n,γ) reaction up to 8 keV neutron energy

Cited by 41 publications

References 33 publications

The temperature and chronology of heavy-element synthesis in low-mass stars

The temperature and chronology of heavy-element synthesis in low-mass stars

On the performance of large monolithic LaCl₃(Ce) crystals coupled to pixelated silicon photosensors

Indirect $$(n, \gamma )^{91,92}$$ Zr Cross Section Measurements for the s-Process

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The93Zr(n,γ) reaction up to 8 keV neutron energy

Cited by 41 publications

References 33 publications

The temperature and chronology of heavy-element synthesis in low-mass stars

The temperature and chronology of heavy-element synthesis in low-mass stars

On the performance of large monolithic LaCl3(Ce) crystals coupled to pixelated silicon photosensors

Indirect $$(n, \gamma )^{91,92}$$ Zr Cross Section Measurements for the s-Process

Contact Info

Product

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On the performance of large monolithic LaCl₃(Ce) crystals coupled to pixelated silicon photosensors