Re: Monitoring/Shielding of 50fs 100 MeV e-

[Lester.Slaback@nist.gov]

>Of interest to me here is a researcher who is developing a laser based
>accelerator. They predict that their next unit may be capable of
>producing essentially monoenergetic 100 MeV electrons in 50-100 fs pulses
>repeated with up to a 1 hz frequency.  I would appreciate any advice you
>could provide about monitoring equipment  Clearly energy dependance,
>saturation, recombination and calibration are big issues.  Fortunately,
>the lab is reasonably well funded.

In the accelerator room the primary need is a system that can demonstrate
the presence of a beam.  For this a very rudimentary system will work. But
with a 1 Hz system it won't be your standard ratemeter. Second, you might
need a system that monitors induced activity. But at 100 fs, 1 Hz, you are
going to need one hellacious peak power to overcome your E-14 duty factor. 
I'll bet that induced activity won't be an issue.


>Certainly shielding is also a big issue.  The beam produced will probably
>be produced with an initial narrow cone (5 cm spread a 50 cm distance).
>Any advice for materials, amounts, shielding codes or references would be
>appreciated.

By far the best reference is IAEA Tech Report 188, particularly for any
neutron production issues.  And, yes, beam intensity is certainly an
important parameter in this assessment.

-- 
the above are the personal musing of the author,
and do not represent any past, current, or future
position of NIST, the U.S. Government, or anyone else
who might think that they are in a position of authority.
NBSR Health Physics
NIST
Gaithersburg, MD 20899
301 975-5810
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Lester.Slaback@nist.gov
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