hit pay dirt

Reader's Digest 6月号の記事 WHY DID THIS INNOCENT MAN PLEAD GUILTY? からの抜粋です。
On Man 16, 2013, the Essex County prosecutor's office ordered investigators to look for the missing rape kit. Just a month later, they hit pay dirt at the New Jerse State Police lab: the original kit, still sealed.
この慣用句 "hit pay dirt" は過去に2度も取り上げていますが（5/24/2016と11/7/2011）、又忘れたので復習です。
・Cambridge Idioms Dictionary: to achieve or discover something important or valuable She finally hit pay dirt with her third novel which quickly became a best seller.
・McGraw-Hill Dictionary of American Idioms and Phrasal Verbs: Fig. to discover something of value. (Alludes to discovering valuable ore.): Sally tried a number of different jobs until she hit pay dirt. I tried to borrow money from a lot of different people. They all said no. Then when I went to the bank, I hit pay dirt.
"hit pay dirt" を忘れる様だから宝くじもさっぱり当たらないのだな。