Re: problems:
Deane D McIntyre (dmcintyr@acs.ucalgary.ca)
Mon, 10 Jun 1996 16:57:59 -0600
In message <Pine.SOL.3.91.960610103623.25835A-100000@maroon.tc.umn.edu> Vikram A
Roongta writes:
>
>
> Hi Bruker Users:
>
> I want to find out if anybody out there has seen the following problems
> on the AMX-600 and AM-250 instruments.
>
> AMX-600: Calibration of the proton pulse is asymmetric. For ex: if HL1=3
> and using PAROPT with p1 starting at 1u and incremented by 1u for 32
> increments. The 90 maximum is reached early at about 8u and 180 is at
> about 20u. The pulse width I usually get is 10u for 90 pulse. I see this
> at all different power levels of the proton e-coupler. It is really bad
> at low power levels like HL1=40 for a 1ms pulse for saturating water in
> watergate sequence. The 90 I get in the last case is at about 700u
> instead of 1000u, but 180 is at 2000u. I have tried everything. Please
> help.
One thing to check is pulse droop. If you have a scope handy, set the
spectrometer up to produce a string of ca. 50-100 us pulses and look
at them on the scope (an attenuator may be requires). Any decrease in
the amplitude of the pulse with time (giving a trapizodial shape to the
pulse) will be apparent. With pulse droop, 180 degree pulses will be
>twice as long as 90 degree pulses, and 360 degree pulses will be >twice
as long as 180 degree pulses.
Cheers, Deane D McIntyre
dmcintyr@acs.ucalgary.ca