[time-nuts] Question on crystal jumps
namichie at gmail.com
Fri Oct 24 05:25:49 UTC 2008
My insight into frequency jumps in xtals is that they may be due to a
of mechanisms, but are within the range of our experience.
When grinding solids the surface is rough so we use decreasing sizes
of grinding medium
to polish through scratches, but a deep chip may leave a partly
attached particle at the surface.
Small microcracks may extend themselves short distances.
Cosmic ray events may implant and atom into the lattice, straining it.
Loose particles may attach to the surface (but then we may see a
reversal as they let go later)
Gold plating may be developing cracks, or loosing particles.
Remember at the very small particle size, the force of attraction to
mass ratio is much higher than
for large particles.
Does chemical etching reduce the frequency of micro-jumps?
Can quartz crystals be thermally annealed?
What is interesting is the ageing mechanisms. Does gross thermal
cycling reduce ageing?
just some thoughts,
On 24/10/2008, at 3:25 PM, SAIDJACK at aol.com wrote:
> Hi Steve,
> the jumps don't anneal themselves, they are permanent changes in
> The crystal is off-frequency after a jump. This has to be
> compensated by
> driving the crystal with a different voltage after the jump.
> See the following plot, blue is phase offset to UTC, brown is EFC
> You can see that the voltage is different after the jump, meaning the
> crystal has physically changed in some way.
> In a message dated 10/23/2008 19:23:54 Pacific Daylight Time,
> sar10538 at gmail.com writes:
> Now if the jumps were caused by something like a cosmic ray, I would
> expect that the xtal would just wobble off frequency rapidly and very
> quickly go back to its resonant frequency. Using a multi-stage xtal
> filter should circumvent this as the particle would have to
> strike all the xtals in the filter on it's path. Physical arrangement
> of the xtals in the filter would easily guard against that.
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