re Light flashes

[HWADE@aol.com]

Kim:

What Paul Frame said is correct. What the other respondent said is not.

Back in the 70's when I was still at LBL, the Director, Ed Mc Millan agreed
to serve as a guinea pig. He positioned his eye in the 900+ Mev alpha
particle cyclotron beam, and yes, he saw flashes, just the the astronauts had
reported. Tom Budinger was involved and  is still at LBL and UC and could
fill details I think. (I don't trust anyone's memory but my own so take what
he may say with a grain of salt) Safety precautions were more than adequate
for the time but now of course it would be essentially impossible to repeat
the experiment because of the plethora of rules and regs ad nauseum. This
episode was written up in the Lab newspaper so it is public knowledge and may
be cited.

Also back in the 70's I arranged for over 70 LBL employees to have a slit
lamp exam. Some, including Luis Alvarez who said he tuned the deuteron beam
of the 37" cyclotron by eye, had been cyclotron workers since the 30's. Some
had recorded neutron exposures upwards of a rem. None showed any evidence of
radiation cataract.
 
There were of course a case or two of radiation cataract among cyclotron
workers at Indiana University from exposures received there during the war.
And radiation cataract was seen in a person or two involved in a criticality
accident at LASL.

In therapeutic radiology the smallest dose that produced a cataract in the
lens of a human eye was slightly more than 300 rad.  Above 1100 rads all
exposed lenses developed cataracts.
Merriam, G.R. and Foch, E.F.  A Clinical Study of Radiation Cataracts and the
Relationship to Dose.  Am. J. Roentgenology.  77, 759 (1957).

For a fuller description of the cyclotron cataract problem see my chapter,
Early Days at the Rad Lab, in A History of Accelerator Protection, Patterson
and Thomas eds., Nuclear Technology Publishing, 1994 

H.Wade Patterson