26g, mAl production cross sections from the 23Na(α, n)26Al reaction

Norman, E. B.; Chupp, T. E.; Lesko, K. T.; Schwalbach, P.; Grant, Patrick

doi:10.1016/0375-9474(82)90283-4

Cited by 23 publications

(25 citation statements)

References 18 publications

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“…Furthermore, it can be seen from the StM calculations in Fig. 56 [143,146]. The lowest data point of Almarez-Calderon et al [146] represents an upper limit only.…”

Section: Thementioning

confidence: 88%

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Cross sections of α-induced reactions for targets with masses A ≈ 20–50 at low energies

Mohr

2015

Eur. Phys. J. A

100

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Abstract. A simple reduction scheme using so-called reduced energies E red and reduced cross sections σ red allows the comparison of heavy-ion induced reaction cross sections for a broad range of masses of projectile and target and over a wide energy range. A global behavior has been found for strongly bound projectiles whereas much larger reduced cross sections have been observed for weakly bound and halo projectiles. It has been shown that this simple reduction scheme works also well for α-particle induced reactions on heavy target nuclei, but very recently significant deviations have been seen for α+ 33 S and α+ 23 Na. Motivated by these unexpected discrepancies, the present study analyses α-induced reaction cross sections for targets with masses A ≈ 20 − 50. The study shows that the experimental data for α-induced reactions on nuclei with A ≈ 20 − 50 deviate slightly from the global behavior of reduced cross sections. However, in general the deviations evolve smoothly towards lower masses. The only significant outliers are the recent data for 33 S and 23 Na which are far above the general systematics, and some very old data may indicate that 36 Ar and 40 Ar are below the general trend. As expected, also the doubly-magic 40 Ca nucleus lies slightly below the results for its neighboring nuclei. Overall, the experimental data are nicely reproduced by a statistical model calculation utilizing the simple α-nucleus potential by McFadden and Satchler. Simultaneously with the deviation of reduced cross sections σ red from the general behavior, the outliers 23 Na, 33 S, 36 Ar, and 40 Ar also show significant disagreement between experiment and statistical model calculation.PACS. 25.55.-e 3H-, 3He-, and 4He-induced reactions -24.10.Pa Thermal and statistical models

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“…Furthermore, it can be seen from the StM calculations in Fig. 56 [143,146]. The lowest data point of Almarez-Calderon et al [146] represents an upper limit only.…”

Section: Thementioning

confidence: 88%

“…Very recently, an updated galactic emission map was derived from the SPI spectrometer data aboard the INTEGRAL mission [140]. Because of a low-lying 0 + isomer in 26 [142,143,146]. Further discussion see text.…”

Section: Namentioning

confidence: 99%

Cross sections of α-induced reactions for targets with masses A ≈ 20–50 at low energies

Mohr

2015

Eur. Phys. J. A

100

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“…We considered the seven most important (α, n) target nuclides, together with spontaneous fission accounting for > 96 % of neutron production. Experimental data from Flynn et al (1978) (EXFOR entires A0509005, A0509007, A0509008) were used for 27 Al,29 Si and 30 Si;Norman et al (1982) (C0731001) data for 23 Na; combined Bair and Willard (1962) (P0120002) and Hansen et al (1967) (P0116003) data for 18 O. 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 %.…”

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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“…The neutron yield of the (α, n) reactions for various elements have been discussed by many authors [39][40][41][42]. The α particles produced from uranium and thorium decays in materials travel with energies in the MeV range.…”

Section: Radiogenic Neutronsmentioning

confidence: 99%

“…Neutrons designated to start in the bulk or on the surface of all the materials of the detector, or surrounding the detector, need to be properly assigned with emission rates and energy spectra, which are crucial in determining the total background events in the ROI. Therefore, the radiogenic neutrons need to be understood very well in terms of their origin, transport, and interaction with different materials.The neutron yield of the (α, n) reactions for various elements have been discussed by many authors [39][40][41][42]. The α particles produced from uranium and thorium decays in materials travel with energies in the MeV range.…”

mentioning

confidence: 99%

High-Energy Neutron Backgrounds for Underground Dark Matter Experiments

Chen¹

2016

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A B S T R A C TDirect dark matter detection experiments usually have excellent capability to distinguish nuclear recoils, expected interactions with Weakly Interacting Massive Particle (WIMP) dark matter, and electronic recoils, so that they can efficiently reject background events such as gamma-rays and charged particles. However, both WIMPs and neutrons can induce nuclear recoils. Neutrons are then the most crucial background for direct dark matter detection. It is important to understand and account for all sources of neutron backgrounds when claiming a discovery of dark matter detection or reporting limits on the WIMP-nucleon cross section. One type of neutron background that is not well understood is the cosmogenic neutrons from muons interacting with the underground cavern rock and materials surrounding a dark matter detector.The Neutron Multiplicity Meter (NMM) is a water Cherenkov detector capable of measuring the cosmogenic neutron flux at the Soudan Underground Laboratory, which has an overburden of 2090 meters water equivalent. The NMM consists of two 2.2-tonne gadolinium-doped water tanks situated atop a 20-tonne lead target. It detects a high-energy (>∼ 50 MeV) neutron via moderation and capture of the multiple secondary neutrons released when the former interacts in the lead target. The multiplicity of secondary neutrons for the high-energy neutron provides a benchmark for comparison to the current Monte Carlo predictions. Combining with the Monte Carlo simulation, the muon-induced high-energy neutron flux above 50 MeV is measured to be (1.3 ± 0.2) × 10 −9 cm −2 s −1 , in reasonable agreement with the model prediction. The measured multiplicity spectrum agrees well with that of Monte Carlo simulation for multiplicity below 10, but shows an excess of approximately a factor of three over Monte Carlo prediction for multiplicities ∼ 10 − 20.In an effort to reduce neutron backgrounds for the dark matter experiment SuperCDMS SNO-LAB, an active neutron veto was developed. It is estimated that the current design of the neutron veto with a 40 cm thick layer of boron-doped liquid scintillator can achieve a > 90% efficiency for tagging the single-scatter neutrons. In addition, a one-quarter scale prototype detector for neutron veto has been built and tested. H I G H -E N E R G Y N E U T R O N B A C K G R O U N D S F O R U N D E R G R O U N D D A R K M A T T E R E X P E R I M E N T S Y U C H E N B . S . , B E I J I N G I N S T I T U T E O F T E C H N O L O G Y , B E I J I N G , C H I N A ( 2 0 0 6 ) M . S . , B E I J I N G N O R M A L U N I V E R S I T Y , B E I J I N G , C H I N A ( 2 0 0 9 ) D I S S E R T A T I O N S U B M I T T E D I N P A R T I A L F U L F I L L M E N T O F T H E R E Q U I R E M E N T S F O R T H E D E G R E E O F D O C T O R O F P H I L O S O P H Y I N P H Y S I C S S Y R A C U S E U N I V E R S I T Y D E C E M B E Dark MatterThere is compelling evidence for the existence of dark matter from astronomical and cosmological observations. In this chater, I will briefly present modern cos...

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26g, mAl production cross sections from the 23Na(α, n)26Al reaction

Cited by 23 publications

References 18 publications

Cross sections of α-induced reactions for targets with masses A ≈ 20–50 at low energies

Cross sections of α-induced reactions for targets with masses A ≈ 20–50 at low energies

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

High-Energy Neutron Backgrounds for Underground Dark Matter Experiments

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