Re: [BLAST_SHIFTS] shift in ion pol mass peaks

From: Hauke Kolster (hauke@lns.mit.edu)
Date: Mon Sep 08 2003 - 19:51:17 EDT


Tancredi,

The WFT seems not to be affected significantly. But I did not have
time to study it with reversed target filed because it eventually
failed to operate.

You certainly need two different SFT setups for both directions.
How repeatable they are after switching field direction is not
clear because we never did this during SFT operation. The limiting
factor here was that there is a significant overhead involved in
switching the direction of the holding fields.

Hauke

On Monday, September 8, 2003, at 12:11 PM, Tancredi Botto wrote:

>
> Hauke,
> how much are we sensitive to the history of the hfield direction in the
> wft and sft units ? And can we optimize the sft and wft orientation
> w.r.t
> the holding field ?
>
> -- t
> _______________________________________________________________________
> _________
> Tancredi Botto, phone: +1-617-253-9204 mobile: +1-978-490-4124
> research scientist MIT/Bates, 21 Manning Av Middleton MA, 01949
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> ^^^^^^^^^
>
> On Mon, 8 Sep 2003, Hauke Kolster wrote:
>
>>
>> Yuan,
>> We recently reversed the target holding field. That means that the
>> direction
>> of the residual field generated at the magnet of the ion polarimeter
>> was also
>> reversed. Did you do calculations for the ion polariemter with the
>> target
>> magnetic field included? What effect do you expect on the magnet of
>> the
>> ion
>> polarimeter? Did you do a hysteresis suppression cycle before you
>> measured
>> the mass peaks?
>>
>> Hauke
>>
>>
>>
>>> But the mysterious thing is that istead of what we got before (MASS 1
>> peak
>>> located at I_WF=1.25A and MASS 2 peak located at I_WF=1.75A), two and
>> only
>>> two peaks were found at I_WF=0.85A and I_WF=1.20A , no matter the
>> long.
>>> holding field was on or off. Since these two I_WF's satisfy the
>> sqare root 2
>>> relation, it seems that somehow the locations of the mass peaks were
>> moved.
>>> More study about this is needed.
>>



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