| Autor: |
Samual Dean Gardner, L. E. Ussery, C. C. Cappiello, R.E. Morgado, C.L. Hollas, Ronald A. Krauss, James M. White, Guy J. Arnone, John D. Zahrt |
| Rok vydání: |
1994 |
| Předmět: |
|
| Zdroj: |
Substance Detection Systems. |
| ISSN: |
0277-786X |
| DOI: |
10.1117/12.171267 |
| Popis: |
115ev122ev(1)The cross section for nitrogen near tbe 9. 17-MeV resonance3'4'5 is shown in Figure 1.The extreme narrowness of this peak in tbe resonance, while representing a unique signature for nitrogen, presents aserious practical problem in genemting an adequate resonant-energ gamma-ray flux for it to be a useful probe. Afterbriefly investigating filtered bremsstrahlung sources, we found them to have adverse signal-to-noise ratios, and this led usto adopt the 13C(P,y)14N reaction6 (tl inverse to resonance absorption) as the preferred gamma-my source. Tho protonsource for this reaction dictates the use ofa particle accelerator and the practicality of tbe approach depeixis largely onachieving sufficiently high proton currents from the accelerator.Because ofthe Doppler shift from the recoiling '4N in the above reaction, only those gamma rays emitted in an0.7-degree-wide beam at 80.7 degrees from tbe direction ofthe proton beam (in tbe laboratory frame of reference) are atthe precise resonance energy. Thus, tbe locus of resonant photons is a narrow 80.7° conical section whose axis coincideswith the proton beam. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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