Beta-plus (Î² +) radiation is the emission of positrons, which are the antimatter form of electrons. When a positron slows to speeds similar to those of electrons in the material, the positron will annihilate an electron, releasing two gamma photons of 511 keV in the process.
The Congressional Budget Office puts the cut-off lower, at $347,000 in 2007, or $252,000 after subtracting federal taxes and adding back transfers. Measured by net worth, rather than income, the top 1% started at $6.9m in 2009, according to the Federal Reserve, down 23% from 2007.
The average annual salary for the 90th percentile (the top 10% highest paid) is $88,330. The median annual salary is $35,080. The average annual salary for the bottom 10% earners is $18,190. We note that the top 10% workers are paid nearly five times more than the bottom 10% workers in the United States.