[d2n-analysis] Target Spin State in Datastream

[Diana Parno]

I think Jin's reply, regarding the error message we're receiving for an 
"Invalid Spin State Signal" in the THaADCHe3Spin class, is quite useful 
regarding what we did and didn't have wired during d2n, so I thought I'd 
share it.

Diana

---------- Forwarded message ----------
Date: Tue, 20 Oct 2009 22:42:11 -0400
From: Jin Huang <jinhuang at jlab.org>
To: 'Diana Parno' <dseymour at andrew.cmu.edu>
Cc: 'Yi Qiang' <yqiang at jlab.org>
Subject: RE: Target Spin State Question

Hi, Diana,...

THaADCHe3Spin is used to read in spin flip spin state signal and put a
target spin flag to each CODA event. In d2n case, spin signal is not
necessary making sense, depending on the setup of the signal. Also, since
there is no spin flip during d2n, it will be OK to just give a spin state
for each run. So I would say just do not load he3.* modules.

The error message was from a internal logical check failure. For a valid
spin signal, there is no chance both signal +/- channels to be logical 1.
Once it happens, a warning message like the one you see is shown. Again,
it's not important at all for d2n.

However, during part of d2n, we tried to set the spin signal to be
consistent with physical spin direction of the target. The advantage of this
effort is to provide a double check with your run by run spin direction
assignment, as well as to identify accidental during-a-run NMR measurements.
Because during NMR, spin signal would set to be "unknown spin state". But
obviously, it is not working well during the run giving these warnings.
However, as I mentioned above, it's not important at all. It's just a double
check.

Cheers,

Jin



-----Original Message-----
From: Diana Parno [mailto:dseymour at andrew.cmu.edu]
Sent: Tuesday, October 20, 2009 3:10 PM
To: Jin Huang
Subject: Target Spin State Question

Hi Jin,

I hope things are going well. I'm also hoping that you might be able to
help us sort out an issue we're having: our analyzer is returning error
messages on the target spin state for every event. For example:

Warning in <THaADCHe3Spin::"he3.ladc1"::Decode>: Invalid Spin State
Signal for he3.ladc1. @ event #99994
Spin Up ADC = 16383.000000 ; Spin Down ADC = 16383.000000
Warning in <THaADCHe3Spin::"he3.bbadc"::Decode>: Invalid Spin State
Signal for he3.bbadc. @ event #99994
Spin Up ADC = 16383.000000 ; Spin Down ADC = 16383.000000

Obviously, there are lots of things that are different in our setup as
compared to yours --  no 20-minute spin flips, separated DAQs (although
this particular run was with a unified DAQ), etc.

Does this look like a problem that you've encountered, or that you have
some quick idea how to solve? Brad thinks that the target spin state was
replicated in a number of places in the datastream; perhaps you could
point us in the right direction for retrieving those.

Thanks for any help you can offer.

Diana