RE: postrons

["Jacobus, John (OD/ORS)" <jacobusj@ors.od.nih.gov>]

It is probably Na-22, which has a half-life of 2.62 years (Other positron

emitters are Na-20 with a half-life of 0.4 seconds, and Na-21 with a

half-life of 23.0 seconds).  It is used in PET imaging for marker sources.



Na-22 decays by positron emission 90% of the time, and electron capture 10%

of the time.  Both decays lead to an excited state of Ne-22.  The excitation

energy is instantly released as a 1.277 MeV gamma ray.



-- John 

John Jacobus, MS

Certified Health Physicist 

3050 Traymore Lane

Bowie, MD  20715-2024



E-mail:  jenday1@email.msn.com (H)      



-----Original Message-----

From: Thomas J Savin [mailto:tjsav@LYCOS.COM]

Sent: Wednesday, August 01, 2001 9:06 AM

To: radsafe@list.vanderbilt.edu

Subject: postrons





I read a brief article in the weekly Scientific American weekly e-mail

newsletter about scanning positron microscope (SPM).  The microscope uses an

isotope of sodium as its positron source.  Does anyone know what isotope it

is and the decay pathway that allows the the release of a positron?  I

searched the web and came up with zero.

. . .

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