Hello All
Thank you so much for this enthusiastic response for my "shimming
management" related questions and I am still getting your answers and
thoughts so I will wait for a few more days and summarize it in my next
posting.
The questions I have now is somewhat related to the shimming and
maintaining the lineshapes :
(1.) How many of you have installed vibration dampers (cheaper donut
ones to expensive TMC legs) on your magnets ?
(2.) What are the tell-tale features you noticed on the lineshape,
that helped you isolate this as a cause against poor/inadequate
transverse shimming?
(3.) How critical did you think these were and how did you
definitvely demonstrate it to the forces-that-might-be (to get the
resources to install the vibration dampers) ?
(My own guess is that people running a range of 1D
spectra perhaps do not complain as much compared to those who run 2D (or
nD) experiments, who may have an aggravated t1-noise issue)
I confess that I have a self-centered motive in asking the above
questions. We faced the unimagineable couple of weeks ago, when one of
our 500 MHz magnets quenched and while we are still soul-searching as
to what had happened, we are getting an Oxford guy come in here to
re-build the magnet and I thought this may be an opportune time to
install an inexpensive vibration damper system to this magnet. Since
this magnet was manufactured in 1985 with no specific structural
features built-in to accomodate vibration dampers of the kind available
now, apparently one may have to drill holes in the legs to retrofit the
dampers and it better be done when the magnet is not in field.
In our case, whenever my helper assistant used to set the 160L
liquid Nitrogen dewar on the floor from the cart or even when a stockily
built person used walk across the room, I could see the lock level show
a blip like this : -------V^v^------- [that's the best I could get for
a wavy line on a text interface :) ]. This is not the case with another
500 system that is in the same hall, which is on a "donut" type
vibration damper.
I am immensely grateful for enduring my continuous questions and
will be very happy to get your thoughts and responses and will also
summarize the same in a future posting.
Best Regards
rajan
--
*_______________________________
Rajan K Paranji, Ph.D.
*NMR Facility Manager
Department of Chemistry
Room 65, Bagley Hall
Univeristy of Washington
*Seattle, WA 98105
ph: 206 685 2581
fax: 206 685 8665
email: paranji_at_chem.washington.edu
___________________________________*
Received on Mon Sep 20 2004 - 09:12:12 MST