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Kruger, S. T.; Heymann, D.

doi:10.1103/physrevc.7.2179

Cited by 9 publications

(54 citation statements)

References 14 publications

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“…Table 1. (Note that the Komarov [1974] result is consistent with earlier work Hyde et al, 1971;Kruger and Heymann, 1973], which indicated that the cross section for the production of very energetic (>95 MeV total energy) 3He is significantly greater than that for equivalent energy nile. )…”

Section: Ramaty and Lingenfelter [1969] Calculated 3he Productionsupporting

confidence: 82%

Energetic helium isotopes trapped in the magnetosphere

Chen¹,

Guzik²,

Wefel³

et al. 1996

J. Geophys. Res.

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Helium nuclei have been measured within the magnetosphere (L ≤ 6) during the 1990/1991 CRRES mission over an energy range of ∼40–100 MeV nucleonl−1. The Office of Naval Research 604 instrument resolves helium isotopes with a mass resolution of ∼0.1 amu. Each helium isotope can be represented by a power law energy spectrum, and the energy spectrum of the 3He is different from that of 4He; that is, the 3He/4He ratio is energy dependent. In the energy range 51–86 MeV/nucleon the 3He/4He ratio is 7.4 ± 2.6 for L = 1.15–1.3 and 2.2±0.6 for L = 1.8–2.15. All observed helium events at L < 2.65 show pitch angle distributions consistent with equatorially trapped ions, whereas the distributions at larger L values are more uniform, within a factor of 2. For 2.15 < L < 6, as L decreases, the 3He/4He ratio increases and the helium energy spectrum softens. A possible origin of the geomagnetically trapped helium isotopes at L <2.15 is proton interactions in the residual atmosphere. The CRRES satellite was operational during the large geomagnetic storm on March 24, 1991, and we have divided the analysis into prestorm and poststorm time periods. Following the storm, the magnetosphere became more dynamic, and at L ∼ 2.3 an enhanced helium flux was observed. Over the energy range of 51–86 MeV nucleonl−1 both the average 3He and 4He fluxes at L = 2.15–2.65 increased by a factor of 6 after the storm relative to the prestorm period, while at L = 1.8–2.15 the average 3He and 4He fluxes decreased by factors of 3 and 11, respectively, following the storm. The implications of these observed results are discussed.

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Section: Ramaty and Lingenfelter [1969] Calculated 3he Productionsupporting

confidence: 82%

Energetic helium isotopes trapped in the magnetosphere

Chen¹,

Guzik²,

Wefel³

et al. 1996

J. Geophys. Res.

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“…ground is typically less than 10 years, cosmogenic isotopes with half-lives greater than 100 years (i.e., 10 Be, 14 C, and 26 Al) do not build up sufficient activity [16,17] to produce significant backgrounds. Thus the cosmogenic isotopes most relevant to silicon-based rare-event searches are tritium, 7 Be, and 22 Na. Tritium is a particularly dangerous background for dark matter searches because it decays by pure beta emission and its low Qvalue (18.6 keV) results in a large fraction of decays that produce low-energy events in the expected dark matter signal region.…”

Section: Cosmogenic Radioisotopesmentioning

confidence: 99%

“…The level of background from cosmogenic isotopes in the final detector is effectively determined by the aboveground exposure time during and following detector production, the cosmic-ray flux, and the isotopeproduction cross sections. The neutron-induced production cross sections for tritium, 7 Be, and to a lesser extent 22 Na, are not experimentally known except for a few measurements at specific energies. There are several estimates of the expected cross sections; however, they vary significantly, leading to large uncertainties in the expected cosmogenic background for rareevent searches that employ silicon detectors.…”

Section: Introductionmentioning

confidence: 99%

Cosmogenic activation of silicon

Saldanha,

Thomas,

Tsang

et al. 2020

Preprint

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The production of 3 H, 7 Be, and 22 Na by interactions of cosmic-ray particles with silicon can produce radioactive backgrounds in detectors used to search for rare events. Through controlled irradiation of silicon CCDs and wafers with a neutron beam that mimics the cosmic-ray neutron spectrum, followed by direct counting, we determined that the production rate from cosmic-ray neutrons at sea level is (112 ± 24) atoms/(kg day) for 3 H, (8.1 ± 1.9) atoms/(kg day) for 7 Be, and (43.0 ± 7.1) atoms/(kg day) for 22 Na. Complementing these results with the current best estimates of activation cross sections for cosmic-ray particles other than neutrons, we obtain a total sea-level cosmicray production rate of (124 ± 24) atoms/(kg day) for 3 H, (9.4 ± 2.0) atoms/(kg day) for 7 Be, and (49.6 ± 7.3) atoms/(kg day) for 22 Na. These measurements will help constrain background estimates and determine the maximum time that silicon-based detectors can remain unshielded during detector fabrication before cosmogenic backgrounds impact the sensitivity of next-generation rare-event searches.

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“…We used the TALYS-1.2 code (Koning et al 2008) to calculate the cross-sections up to an incident proton energy of 240 MeV. In addition we used the experimental data from Kruger & Heymann (1973) at 600 MeV and 3 GeV. The TALYS-1.2 calculation shows two local maxima in the range 19-22 MeV and 46-190 MeV.…”

Section: Cross-sections For Protonmentioning

confidence: 99%

“…We instead constructed the excitation function by logarithmically interpolating the regions above and below each maximum. In addition, we increased the thus modified TALYS results by a factor of 2.6 to obtain a smooth transition between modeled and measured crosssections (Kruger & Heymann 1973). Finally, we extended the excitation function to 10 GeV by logarithmic extrapolation; the thus determined cross-section at 10 GeV is 43 mb.…”

Section: Cross-sections For Protonmentioning

confidence: 99%

Production and Recoil Loss of Cosmogenic Nuclides in Presolar Grains

Trappitsch

Leya

2016

ApJ

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Presolar grains are small particles that condensed in the vicinity of dying stars. Some of these grains survived the voyage through the interstellar medium (ISM) and were incorporated into meteorite parent bodies at the formation of the Solar System. An important question is when these stellar processes happened, i.e., how long presolar grains were drifting through the ISM. While conventional radiometric dating of such small grains is very difficult, presolar grains are irradiated with galactic cosmic rays (GCRs) in the ISM, which induce the production of cosmogenic nuclides. This opens the possibility to determine cosmic-ray exposure (CRE) ages, i.e., how long presolar grains were irradiated in the ISM. Here, we present a new model for the production and loss of cosmogenic 3 He, 6,7 Li, and 21,22 Ne in presolar SiC grains. The cosmogenic production rates are calculated using a state-of-the-art nuclear cross-section database and a GCR spectrum in the ISM consistent with recent Voyager data. Our findings are that previously measured 3 He and 21 Ne CRE ages agree within the (sometimes large) 2σ uncertainties and that the CRE ages for most presolar grains are smaller than the predicted survival times. The obtained results are relatively robust since interferences from implanted low-energy GCRs into the presolar SiC grains and/or from cosmogenic production within the meteoroid can be neglected.

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High-Energy Proton Production ofH3,He

Cited by 9 publications

References 14 publications

Energetic helium isotopes trapped in the magnetosphere

Energetic helium isotopes trapped in the magnetosphere

Cosmogenic activation of silicon

Production and Recoil Loss of Cosmogenic Nuclides in Presolar Grains

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