The absolute cross sections of the 39K(n, p)39Ar and 39K(n, α)36Cl reactions for 2.46 MeV neutrons

Johnson, P.B.; Chapman, N.G.; Callaghan, J.E.

doi:10.1016/0375-9474(67)90436-8

Cited by 11 publications

(3 citation statements)

References 9 publications

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“…In the case of 25 Mg and 26 Mg where no experimental data are available in the EXFOR database, we arbitrarily set the uncertainty at 10 %. The experimental 39 K(n, p) cross section dataset is constructed from Johnson et al (1967) and Bass et al (1964) experimental data. Nolte et al (2006) report a non-zero 39 K(n, p) 39 Ar cross section in the epithermal energy range.…”

Section: Uncertainty In the Calculationmentioning

confidence: 99%

Subterranean production of neutrons, 39Ar and 21Ne: Rates and uncertainties

Šrámek

Stevens

McDonough

et al. 2017

Geochimica et Cosmochimica Acta

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Accurate understanding of the subsurface production rate of the radionuclide 39 Ar is necessary for argon dating techniques and noble gas geochemistry of the shallow and the deep Earth, and is also of interest to the WIMP dark matter experimental particle physics community. Our new calculations of subsurface production of neutrons, 21 Ne, and 39 Ar take advantage of the state-of-the-art reliable tools of nuclear physics to obtain reaction cross sections and spectra (TALYS) and to evaluate neutron propagation in rock (MCNP6). We discuss our method and results in relation to previous studies and show the relative importance of various neutron, 21 Ne, and 39 Ar nucleogenic production channels. Uncertainty in nuclear reaction cross sections, which is the major contributor to overall calculation uncertainty, is estimated from variability in existing experimental and library data. Depending on selected rock composition, on the order of 10 7 -10 10 α particles are produced in one kilogram of rock per year (order of 1-10 3 kg −1 s −1 ); the number of produced neutrons is lower by ∼ 6 orders of magnitude, 21 Ne production rate drops by an additional factor of 15-20, and another one order of magnitude or more is dropped in production of 39 Ar. Our calculation yields a nucleogenic 21 Ne/ 4 He production ratio of (4.6 ± 0.6) × 10 −8 in Continental Crust and (4.2 ± 0.5) × 10 −8 in Oceanic Crust and Depleted Mantle. Calculated 39 Ar production rates span a great range from 29 ± 9 atoms kg-rock −1 yr −1 in the K-Th-U-enriched Upper Continental Crust to (2.6±0.8)×10 −4 atoms kg-rock −1 yr −1 in Depleted Upper Mantle. Nucleogenic 39 Ar production exceeds the cosmogenic production below ∼ 700 meters depth and thus, affects radiometric ages of groundwater. The 39 Ar chronometer, which fills in a gap between 3 H and 14 C, is particularly important given the need to tap deep reservoirs of ancient drinking water.

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Section: Uncertainty In the Calculationmentioning

confidence: 99%

Subterranean production of neutrons, 39Ar and 21Ne: Rates and uncertainties

Šrámek

Stevens

McDonough

et al. 2017

Geochimica et Cosmochimica Acta

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“…The corresponding cross-sections, taken from several cross-section libraries, are shown in Fig. 11, together with measurements available in the literature [91][92][93][94][95][96][97][98]. At this point, it should be noted, however, that one publication reports a measurement at thermal energies of 32 ±16 mb [99].…”

Section: Productionmentioning

confidence: 99%

“…Figure 13 shows for a (hypothetical) 100-g sample 302 Fig. 11 Cross-sections for the reaction 39 K (n,p) 39 Ar as deduced from several cross-section libraries (JENDL-3.2, ADL-3T), compared to available experimental data [91][92][93][94][95][96][97][98] Expected counting rates in 1998 due to neutron-induced 39 Ar activity, for a beta-detector efficiency of 60%. Calculations were performed using DS86 neutron spectra, a bomb yield of 15 kt, an evaluated cross-section taken from the JENDL-3.2 library, and a hypothetical gravestone sample of 100 g. A typical background counting rate is shown for comparison.…”

Section: Productionmentioning

confidence: 99%

The dosimetry system DS86 and the neutron discrepancy in Hiroshima - historical review, present status, and future options

Rühm¹,

Kellerer²,

Korschinek

et al. 1998

Radiation and Environmental Biophysics

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The historical development of the dosimetry systems for Hiroshima and Nagasaki is outlined from the time immediately after the A-bomb explosions to the publication of the dosimetry system DS86 in 1987, and the present status of the so-called Hiroshima neutron discrepancy is summarized. Several long-lived radionuclides are discussed with regard to their production by neutrons from the A-bomb explosions. With the exception of 63Ni, these radionuclides have not, up to now, been measured in samples from Hiroshima and Nagasaki. Two of them, 63Ni in copper samples and 39Ar in granite samples, were predominantly produced by fast neutrons. 63Ni can be determined by accelerator mass spectrometry with a gas-filled analyzing magnet. It should be measurable, in the near future, in copper samples up to 1500 m from the hypocenter in Hiroshima. 39Ar can be measured in terms of low-level beta-counting. This should be feasible up to a distance of about 1000 m from the hypocenter. Three radionuclides, 10Be, 14C, and 59Ni, were produced predominantly by thermal neutrons with smaller fractions due to the epithermal and fast neutrons, which contribute increasingly more at larger distances from the hypocenter. State-of-the-art accelerator mass spectrometry is likely to permit the determination of 10Be close to the hypocenter and of 14C up to a distance of about 1000 m. 59Ni should be detectable up to a distance of about 1000 m in terms of accelerator mass spectrometry with a gas-filled magnet. The measurements of 10Be, 14C, 39Ar, 59Ni -- and potentially of 131Xe -- can be performed in the same granitic sample that was already analyzed for 36Cl, 41Ca, 6Co, 152Eu, and 154Eu. This will provide extensive information on the neutron spectrum at the specified location, and similarly complete analyses can conceivably be performed on granite samples at other locations.

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Excitation functions for potassium isotopes

Manokhin¹,

Blokhin²

Low Energy Neutrons and Their Interaction With Nuclei and Matter. Part 2

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The absolute cross sections of the 39K(n, p)39Ar and 39K(n, α)36Cl reactions for 2.46 MeV neutrons

Cited by 11 publications

References 9 publications

Subterranean production of neutrons, 39Ar and 21Ne: Rates and uncertainties

Subterranean production of neutrons, 39Ar and 21Ne: Rates and uncertainties

The dosimetry system DS86 and the neutron discrepancy in Hiroshima - historical review, present status, and future options

Excitation functions for potassium isotopes

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