Method and composition of matter for detecting large quantities of paper currency
US5057268A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 19, 1990 |
| Grant date | Oct 15, 1991 |
| Priority date | — |
| Expiry date | Dec 19, 2010 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG07D7/14
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Paper notes used as a monetary currency are deuterated. The level of deuteration while not complete, is high. For U.S. currency the level of deuteration is at least 0.1 mg of deuterium for each one dollar in value of the currency note, and preferably at least 0.3 mg. Use of X-ray or gamma ray interrogation with a beam energy above 2 MeV produces a nuclear reaction releasing a neutron from the deuterium nucleus. If the currency is in large concentrations, e.g. $100,000 or more, the neutrons emitted by this reaction are reliably detectable. The deuteration occurs in the cellulose fibers forming the currency. To resist an exchange of hydrogen atoms for deterium atoms, the deuterium atoms can be used in the formation of synthetic cellulose where the deuterium is more deeply buried within the cellulose molecule than in naturally occurring cellulose. The deuterated synthetic fibers are blended with natural, non-deuterated fibers to form the paper. The currency can also include a mechanism, such as dye, to signal attempts to use solvents or otherwise facilitate any such hydrogen substitution.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.