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<jats:title>Abstract</jats:title> <jats:p>Rare information on photodisintegration reactions of nuclei with mass numbers <jats:italic>A</jats:italic> ≈ 160 at astrophysical conditions impedes our understanding of the origin of <jats:italic>p</jats:italic>-nuclei. Experimental determination of the key (<jats:italic>p</jats:italic>, <jats:italic>γ</jats:italic>) cross sections has been playing an important role in verifying nuclear reaction models and providing rates of relevant (<jats:italic>γ</jats:italic>, <jats:italic>p</jats:italic>) reactions in the <jats:italic>γ</jats:italic> process. In this paper we report the first cross-section measurements of <jats:sup>160</jats:sup>Dy(<jats:italic>p</jats:italic>, <jats:italic>γ</jats:italic>)<jats:sup>161</jats:sup>Ho and <jats:sup>161</jats:sup>Dy(<jats:italic>p</jats:italic>, <jats:italic>n</jats:italic>)<jats:sup>161</jats:sup>Ho in the beam energy range of 3.4–7.0 MeV, partially covering the Gamow window. Such determinations are possible by using two targets with various isotopic fractions. The cross-section data can put a strong constraint on the nuclear level densities and gamma strength functions for <jats:italic>A</jats:italic> ≈ 160 in the Hauser–Feshbach statistical model. Furthermore, we find the best parameters for TALYS that reproduce the available <jats:italic>A</jats:italic> ∼ 160 data, <jats:sup>160</jats:sup>Dy(<jats:italic>p</jats:italic>, <jats:italic>γ</jats:italic>)<jats:sup>161</jats:sup>Ho and <jats:sup>162</jats:sup>Er(<jats:italic>p</jats:italic>, <jats:italic>γ</jats:italic>)<jats:sup>163</jats:sup>Tm, and recommend the constrained <jats:sup>161</jats:sup>Ho(<jats:italic>γ</jats:italic>, <jats:italic>p</jats:italic>)<jats:sup>160</jats:sup>Dy reaction rates over a wide temperature range for <jats:italic>γ</jats:italic> process network calculations. Although the determined <jats:sup>161</jats:sup>Ho(<jats:italic>γ</jats:italic>, p) stellar reaction rates at the temperature of 1 to 2 GK can differ by up to one order of magnitude from the NON-SMOKER predictions, it has a minor effect on the yields of <jats:sup>160</jats:sup>Dy and accordingly the <jats:italic>p</jats:italic>-nuclei, <jats:sup>156,158</jats:sup>Dy. A sensitivity study confirms that the cross section of <jats:sup>160</jats:sup>Dy(<jats:italic>p</jats:italic>, <jats:italic>γ</jats:italic>)<jats:sup>161</jats:sup>Ho is measured precisely enough to predict yields of <jats:italic>p</jats:italic> nuclei in the <jats:italic>γ</jats:italic> process.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We report that the number of &gt;500 MeV protons (<jats:italic>N<jats:sub>g</jats:sub> </jats:italic>) inferred from sustained gamma-ray emission (SGRE) from the Sun is significantly correlated with that of protons propagating into space (<jats:italic>N</jats:italic> <jats:sub>SEP</jats:sub>) as solar energetic particles (SEPs). Under the shock paradigm for SGRE, shocks driven by coronal mass ejections (CMEs) accelerate high-energy protons sending them toward the Sun to produce SGRE by interacting with the atmospheric particles. Particles also escape into the space away from the Sun to be detected as SEP events. Therefore, the significant <jats:italic>N</jats:italic> <jats:sub>SEP</jats:sub>–<jats:italic>N</jats:italic> <jats:sub> <jats:italic>g</jats:italic> </jats:sub> correlation (correlation coefficient 0.77) is consistent with the common shock origin for the two proton populations. Furthermore, the underlying CMEs have properties akin to those involved in ground level enhancement events indicating the presence of high-energy (up to ∼GeV) particles required for SGRE. We show that the observed gamma-ray flux is an underestimate in limb events (central meridian distance &gt;60°) because SGRE sources are partially occulted when the emission is spatially extended. With the assumption that the SEP spectrum at the shock nose is hard and that the 100 MeV particles are accelerated throughout the shock surface (half width in the range 60°–120°) we find that the latitudinal widths of SEP distributions are energy dependent with the smallest width at the highest energies. Not using the energy-dependent width results in an underestimate of <jats:italic>N</jats:italic> <jats:sub>SEP</jats:sub> in SGRE events occurring at relatively higher latitudes. Taking these two effects into account removes the apparent lack of <jats:italic>N</jats:italic> <jats:sub>SEP</jats:sub>–<jats:italic>N</jats:italic> <jats:sub> <jats:italic>g</jats:italic> </jats:sub> correlation reported in previous studies.</jats:p>