Re: Magnetic field interference

[Keith Welch <welch@jlab.org>]

John,

PM tubes are definitely subject to magnetic interference.  They usually
have mu metal shielding, but a strong RF or magnetic field can wreak
havoc.  We have to be very careful surveying around magnets with our
scintillation based survey meters.  The typical response is a nice,
smooth drop in the indicated dose rate as you approach the field. 
Somewhere I have some test data from some field "experiments" we did a
few years ago.  I could probably dig it up if you're interested.  We got
some rough numbers on field strength required to cause problems
(although it's specific to certain instruments, not necessarilly
universal).
 
> Has anyone run across interference on PMT's that was due to magnetic fields?
> If so,  I would appreciate any information you could forward to me.  

> John L. Salladay, CHP
> jlsalladay@mail.ports.navy.mil

-- 
Keith Welch
Thomas Jefferson National Accelerator Facility
Newport News VA
welch@jlab.org
Ph: (757)269-7212
FAX:(757)269-5048
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