Nov 14 2007
GLAST Calibration
The Stanford Linear Accelerator Center has an interesting article dated October 17, called “By the Light of the Moon”, by Amber Dance of SLAC Today, which can be viewed at the following site: http://today.slac.stanford.edu/feature/2007/the-moon.asp.
The article states that the moon is “an object with an absolutely known gamma-ray output”, – likely from EGRET data from the 1990’s, and notes that “The moon would be especially useful for calibrating GLAST,”. Stanford physicist Igor Moskalenko is quoted as saying “Using the moon as a calibrator, you can always be sure that your data are accurate.”
An email I received from a NASA scientist in April 2006, in response to one of my own, said that “the gamma radiation from the Moon was consistent with a conventional model in which cosmic rays hitting the lunar surface produce neutral pi mesons that decay immediately into gamma rays.”, and recommended that I “look elsewhere for possible evidence for gravity photons”.
The question I have is how could the moon be used to calibrate GLAST if it were glowing at an energy of >100 MeV as a result of cosmic ray bombardment? The bombardment hitting the moon could not possibly be uniform enough from all directions such that it produces a gamma ray output that is steady enough at all times, and in all places where there is a relatively quiet background, so that it can be used to calibrate an instrument.
I contend that the moon has a constant known output of gamma rays because of gravitational output, with the energy centered at 312.76 MeV.