Not to mention the way DHS R&D procurements work:
1 - allocate an absurd fraction of the money and time it actually will take
2 - rush out a half-baked RFP
3 - modify and/or withdraw it repeatedly
4 - finally accept white papers
5 - deposit all white papers into a black hole
6 - give the funding to two or three of the politically connected usual suspects
7 - pull the plug, after finally realizing that once again nothing they've come up with will be workable
8 - repeat

And the whole exercise is pointless anyway because there's nothing resembling quality assurance in the explosives screening process. (See above 5-8 for what has been going on since pre-9/11 days with proposals for QA.)