Cross sections of neon isotopes induced by 5, 7, 16, and 19 MeV neutrons

Lavielle, B.; Sauvageon, H.; Bertin, P.Y.; Haouat, G.

doi:10.1103/physrevc.42.305

Cited by 9 publications

(9 citation statements)

References 8 publications

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“…Cross sections for the production of Ne-isotopes from Mg were measured by Reedy et al (1979) and by Lavielle et al (1990) covering neutron energies from 5 to 19 MeV and for 14C from 0 and 26Al from Si up to En = 28 MeV by Imamura et al (1990). In the future, it will be necessary to combine our consistent and validated neutron cross section data base with experimental data from these measurements and from evaluated neutron cross section files.…”

Section: Thin-target Production Cross Sectionsmentioning

confidence: 98%

On the production of cosmogenic nuclides in meteoroids by galactic protons

Michel¹,

Dragovitsch²,

Cloth³

et al. 1991

Meteoritics

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Abstract-A purely physical model is presented describing the depth-and size-dependence of the production of cosmogenic nuclides in meteoroids with radii up to 85 ern and in planetary surfaces by galactic cosmic ray protons. The model is based on Monte Carlo calculations of the intra-and internuclear cascades, by which depth-and size-dependent spectra of primary and secondary protons and of secondary neutrons are derived, and on experimental and theoretical thin-target cross sections of the underlying nuclear reactions. Model calculations are presented for production rates of "Mn, 26A1, 22Ne, and 21Ne in H-and L-chondrites and of "Mn and 26Al in lunar surface material and compared with experimental data. From the analysis of "Mn and 26AI in the Apollo 15 lunar drill core and in the L-chondrite Knyahinya GCR p-spectra and integral particle fluxes at I A.U. and in the meteoroid orbits averaged over the last 10 Ma are derived. An analysis of experimental depth profiles in four H-and L-chondrites demonstrates, that the new model is well capable of describing depth-and size-dependences of production rates of cosmogenic nuclides. Moreover, it is possible to determine exposure ages for these meteorites on the basis of the theoretical i'Ne production rates. The model calculations further explain the depth-and size-dependence of22Ne/ 21 Ne-ratios and the dependences on these ratios of 21Ne, 26AI and 5JMn production rates. The future requirements for model calculations of cosmogenic nuclide production rates in extraterrestrial matter are outlined.

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Section: Thin-target Production Cross Sectionsmentioning

confidence: 98%

On the production of cosmogenic nuclides in meteoroids by galactic protons

Michel¹,

Dragovitsch²,

Cloth³

et al. 1991

Meteoritics

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“…For the neutron-induced reactions there are (practically) no experimental cross sections available, notable exceptions are (Reedy et al 1979;Lavielle et al 1990;Nakamura et al 1992). However, none of the cross sections measured in these studies are relevant for cosmogenic nuclide production in iron meteorites.…”

Section: Cross Sectionsmentioning

confidence: 99%

“…Unfortunately the modeled production rate ratio P( 26 Al)/ P( 21 Ne), used for the 26 Al-21 Ne dating method is depth dependent and ranges between 250 and 650, i.e., it varies by a factor of 2.6. However, the fact that this system has nevertheless been successfully applied to iron meteorites (Graf et al 1987;Lavielle et al 1990), is probably due to the fact that 1) the depth and size dependence of the P( 26 Al)/ P( 21 Ne) ratio is slightly overestimated by the model due to the fact that some of the model predictions are still a priori and 2) that the range modeled by us is for all radii and shielding depths, i.e., the model covers a much wider range of shielding conditions than usually done by meteorite samples. Considering only small to medium sized bodies and intermediate shielding, as expected due to atmospheric ablation of the outermost parts, significantly reduces the possible range.…”

Section: Cosmic-ray Exposure Agesmentioning

confidence: 99%

“…Ages determined via the 10 Be-21 Ne system not only depend on shielding but also on the minor element chemistry, which causes problems for cosmic ray exposure dating. This system should be used with caution if the chemistry of the sample is unknown even if the resultant ages seem to be in agreement with other systems (e.g., Lavielle et al 1990). Our model calculations show, e.g., that assuming a chemical composition of 92% Fe, 7% Ni, and 1% S results in P( 10 Be)/ P( 21 Ne) ratios ranging between 171 and 298.…”

Section: Cosmic-ray Exposure Agesmentioning

confidence: 99%

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New model calculations for the production rates of cosmogenic nuclides in iron meteorites

Ammon

Masarik

Leya

2009

Meteorit & Planetary Scien

100

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Abstract-Here we present the first purely physical model for cosmogenic production rates in iron meteorites with radii from 5 cm to 120 cm and for the outermost 1.3 m of an object having a radius of 10 m. The calculations are based on our current best knowledge of the particle spectra and the cross sections for the relevant nuclear reactions. The model usually describes the production rates for cosmogenic radionuclides within their uncertainties; exceptions are 53 Mn and 60 Fe, possibly due to normalization problems. When an average S content of about 1 ± 0.5% is assumed for Grant and Carbo samples, which is consistent with our earlier study, the model predictions for 3 He, 21 Ne, and 38 Ar are in agreement. For 4 He the model has to be adjusted by 24%, possibly a result of our rather crude approximation for the primary galactic α particles. For reasons not yet understood the modeled 36 Ar/ 38 Ar ratio is about 30-40% higher than the ratio typically measured in iron meteorites. Currently, the only reasonable explanation for this discrepancy is the lack of experimentally determined neutron induced cross sections and therefore the uncertainties of the model itself. However, the new model predictions, though not yet perfect, enable determining the radius of the meteoroid, the exposure age, the sulphur content of the studied sample as well as the terrestrial residence time. The determination of exposure ages is of special interest because of the still open question whether the GCR was constant over long time scales. Therefore we will discuss in detail the differences between exposure ages determined with different cosmogenic nuclides. With the new model we can calculate exposure ages that are based on the production rates (cm 3 STP/(gMa)) of noble gases only. These exposure ages, referred to as noble gas exposure ages or simply 3,4 21 Ne, and 38 Ar but equal to the 36 Ar age. These differences can either be explained by our still insufficient knowledge of the neutron-induced cross sections or by a long-term variation of the GCR.

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“…Except for some experimental neutron cross sections measured by Lavielle et al (1990) for the production of Kr isotopes there are no experimental cross sections for the production of krypton and Xe isotopes by neutron-induced reactions. We had to rely nearly completely on theoretical ones for the a priori calculations.…”

mentioning

confidence: 99%

Production of krypton and xenon isotopes in thick stony and iron targets isotropically irradiated with 1600 MeV protons

Gilabert

Lavielle

Michel

et al. 2002

Meteorit & Planetary Scien

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Abstract-Two spherical targets made of gabbro with a radius of 25 ern and of steel with a radius of 10 cm were irradiated isotropically with 1600 MeV protons at the SATURNE synchrotron at Laboratoire National Satume (LNS)/CEN Saclay, in order to simulate the production of nuclides in meteorites induced by galactic cosmic-ray protons in space. These experiments supply depth-dependent production rate data for a wide range of radioactive and stable isotopes in up to 28 target elements. In this paper, we report results for 78Kr, 80-86Kr isotopes in Rb, Sr, Y and Zr and for 124Xe, 126Xe, 128-132Xe, 134Xe, 136Xeisotopes in Ba and La. Krypton and xenon concentrations have been measured at different depths in the spheres by using conventional mass spectrometry. Based on Monte-Carlo techniques, theoretical production rates are calculated by folding depth-dependent spectra ofprimary and secondary protons and secondary neutrons with the excitation functions of the relevant nuclear reactions. The comparison ofthe model calculation results with experimental data in the thick target experiments performed at LNS and previously at CERN have allowed adjustments of the poorly known excitation functions ofneutron-induced reactions. Thus, for the two experiments at SATURNE, excellent agreement is obtained between experimental and calculated production rates for most Kr and Xe isotopes in all investigated target elements. Only Xe production in Ba in the gabbro is underestimated by the calculations by -25%. This work validates the approach of the thin-target model calculations of cosmogenic nuclide production rates in the attempt ofmodeling the interaction of galactic cosmic-ray protons with stony and iron meteorites in space as well as with lunar samples.

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Cross sections of neon isotopes induced by 5, 7, 16, and 19 MeV neutrons

Abstract: Neutron-irradiated targets of natural magnesium have been analyzed by mass spectrometry in order to determine the excitation functions of neon from the energy threshold up to 20 MeV. Production cross sections of ' Ne isotopes were measured at 5.20, 7.00, 16.20, and 19. 05 MeV.

Cited by 9 publications

References 8 publications

On the production of cosmogenic nuclides in meteoroids by galactic protons

On the production of cosmogenic nuclides in meteoroids by galactic protons

New model calculations for the production rates of cosmogenic nuclides in iron meteorites

Production of krypton and xenon isotopes in thick stony and iron targets isotropically irradiated with 1600 MeV protons

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