Experimental Physics and
Industrial Control System

"Rarback, Harvey M." <[email protected]> · Mon, 20 Jun 2011 12:21:04 -0700

	Folks,

Let me add another data point to the vulnerability of SSI encoders inside the beam tunnel near beam height.  We've had *seven* unrecoverable TR Electronics LT Series failures as well as a few Hall effect limit switch failures at SPEAR.  Shielding with ~1 cm of Pb seems to have fixed (or slowed down?) the failure rate.

Potentiometers and LVDTs inside the tunnel make a great deal of sense.

                              --Harvey
----
Harvey Rarback                   phone: (650)926-3963
SLAC National Accelerator Lab    fax:   (650)926-4100
2575 Sand Hill Road              home phone: (650)560-9111
Menlo Park, CA 94025             [email protected]
                                 http://ssrl.slac.stanford.edu/~rarback

   "Always tell the truth, that way you don't have to keep track."
                            Pogo

> -----Original Message-----
> From: [email protected] [mailto:tech-talk-
> [email protected]] On Behalf Of Hu, Yong
> Sent: Monday, June 20, 2011 9:24 AM
> To: [email protected]; Josh Stein; Richard Farnsworth;
> [email protected]; [email protected]
> Cc: [email protected]
> Subject: RE: radiation damage to electronics inside accelerator tunnel?
> 
> Thanks a lot for all of you sharing experiences and giving suggestions
> which are really helpful for me to convince our Diagnostics Group to
> re-design cabling and shielding.
> 
> Regarding position measurement encoder, we're going to use Potentiometer
> and LVDT with stepper motor for beam diagnostics (slits, scrapers,
> etc.). We think these kinds of analog encoders might have better
> resistance to EMI and radiation.
> 
> Yong

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System