## Electronic Supplementary Information  
* **Figure S1. ** Screen shots of cross-section data plots accessed via NNDC/BNL for reactions that can be induced in \({}^{\mathrm{nat}}\)Y by low-energy protons. (_p_,_n_)\({}^{89g}\)Zr: blue, dark gray [29; 30; 31; 32; 33; 34; 35; 36]; (_p_,_n_)\({}^{89m}\)Zr: dark yellow, light gray [36; 53]; (_p_,_2_n_)\({}^{88}\)Zr: green [29; 54; 55; 56; 57; 58; 59; 60; 61]; (_p_,_n_+_p_)\({}^{88}\)Y: red, light blue, maroon, violet [29; 30; 31; 32; 35; 55; 56; 57; 58; 59; 60; 61]. Some data sets included the contribution from isomeric transition, and some did not. **Table S1. ** Results from publications focused on \({}^{89}\)Zr production using the \({}^{nat}\)Y(\(p\),\(n\)) reaction route, sorted by publication date from newest to oldest. \begin{tabular}{l l l l l l l l l} \hline  & **Y Feil** & **Bombardment** & **Target Holder** & **Target Cooling** & **Activity/** & **\% Recovery** & **Radionucleotide** & **ESA** \\  & **Thickness** & **Parameters** & **Description** & **Description** & **(pA \(\times\) h)** & & **Parity** & \\ \hline  & mm & \(\mu\)A \(\times\) h & & & & mCi/ & & \% of total & mCi-ymol\({}^{-1}\) \\  & & & & & & (uA \(\times\) h) & & activity & (\% of TSA) \\ \hline This Work & 2013 & 0.64 & \(15\times 4\)\({}^{\dagger}\) = 60 & Machined Nb & Chilled water (2.2 \({}^{\circ}\)C); & 3.67-15 & 93\% \({}^{\dagger}\) & 99.998\% & 5-353 \\  & & & & He jet (beam side) & & & & (0.01\%\(\rightarrow\)0.88\%) \\ \hline [PERSON], _et al._[20] & 2011 & 0.15 & \(12\times 2\) = 24 & Aluminum & Chilled water; & 0.338 & 97.5\% & \(>\)95\% & - \\  & & & & He jet (beam side) & & & & \\ \hline [PERSON], _et al._[21] & 2009 & 0.009 & 0.54 \(\times\) 2.3 = 1.3 & - & - & - & - & - & - \\ [PERSON], _et al._[22] & 2007 & 13 & \(2\times 5\) = 10 & Covered with & Chilled water (13 \({}^{\circ}\)C) & 0.754 & 97.5\% & 99.9\% & - \\  & & (Y\({}_{3}\)O\({}_{1}\) pellet diam.) & & Al foil & & & & & \\ \[PERSON], _et al._[23] & 2005 & 0.10 & \(15\times 5\) = 75 & \(10^{\circ}\)slant & Chilled water (25 \({}^{\circ}\)C) & 1.52 & 99.5\% \({}^{\dagger}\) & 99.9\% & 470-1195 \\  & & & & & & & (1.2\%\(\rightarrow\)3.0\%) \\ \[PERSON], _et al._[24] & 2003 & 0.035 & \(80\times 3\) = 240 & onto Cu plate & - & 0.002 & 97\% \({}^{\ddagger}\) & 99.9\% & - \\  & & (sputtered) & & & & & & \\ [PERSON], _et al._[25] & 1994 & 0.025 & \(100\times 1\) = 100 & onto Cu plate & - & 0.069 & 98\% \({}^{\ddagger}\) & - & - \\  & & (sputtered) & & & & & & \\ \hline DeJesus and Nickles [26] & 1990 & 0.127 and 0.6 & \(10\times 2\) = 20 & - & Chilled water & 43 and 100 & 95\% & 87\% & - \\ [PERSON], _et al._[27] & 1986 & - & \(10\times 0.66=6.7\) & - & - & 10.51 & 25\%\(\rightarrow\)80\% & 99\% & - \\ \hline \end{tabular}   
ESA: effective specific activity TSA: theoretical specific activity, (40 Ci-ymol\({}^{-1}\) for \({}^{89}\)Zr). We selected the highest recovery from the productions that are presented in this table. \({}^{\ddagger}\) longest bombardment; \({}^{\ddagger}\) average recovery; \({}^{\ddagger}\) total recovery from multiple fractions. **Figure S2. ** Results of a Monte Carlo simulation [28] of 14.7 MeV protons (\(N\) = 1,000), travelling from left to right, as they pass through a 0.64 mm thick Y foil (Layer 1), and stopping within 0.3 mm after entering the Nb base of the target holder (Layer 2). The entire thickness of the base (4.83 mm) is not shown. This diagram assumes that the Y foil is perfectly in contact with the Nb base. **Table S2. ** Relevant characteristics for reactions that can be induced by 14.7 MeV protons in a \({}^{\mathrm{nat}}\)Y foil target.