Hello,
in (e,e'n) the retiming/Wch start will come from e'.
Also, the retiming takes away pathlength differences for particles that
are always ultra-relativistic and of constant velocity. In the case of
the neutron bars/lads even for the same hit (bar, position) we will have
a range of neutron momenta and therefore different time-of-flights. So it
won't be possible to have the NC arm-trigger come always at the same time.
That jitter will saturate the difference due to different pathlengths since
you can in principle detect neutrons with drastically different velocities
(factors 2-4)
But we have to make sure that for ultra-relativistics particles we measure
a low enough tdc channel
-- tancredi
________________________________________________________________________________
Tancredi Botto, phone: +1-617-253-9204 mobile: +1-978-490-4124
research scientist MIT/Bates, 21 Manning Av Middleton MA, 01949
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
On Thu, 21 Nov 2002, Timothy Smith wrote:
>
> Hello Karen,
>
> At the very worst it means we would need to write
> 56 lines in the electronics.map file. If it was deemed necessary,
> to be neater we could have a LAD section of the parser. We already
> parse each detector package slightly differently.
>
> One question about the "LADS fired" signal. This is a trigger
> signal. Will it have the nice "retiming" propreties - or do we
> just expect the ToF still to always generate the tigger time?
>
> Tim
>
>
> On Thu, 21 Nov 2002, Karen Dow wrote:
>
> >
> > Miro Plesko is designing a special module for the LADS neutron bars
> > that will take analog tube signals, discriminate them, AND the bar ends,
> > OR all bars, and provide a number of outputs: TDC stops, scalers, and a
> > "LADS fired" bit for the sector MLU.
> >
> > Space constraints on the board will force us to wire the input and
> > output signals in a different pattern than the existing TOFs and neutron
> > bars. Rather than having all "top" tubes in a group, and all "bottom"
> > tubes in another group, LADS will have alternating "top" and "bottom"
> > tubes. This has implications for the electronics.map; instead of (LADS
> > left top) being in TDC channels 0-27, and (LADS left bottom) in channels
> > 32-59, the top tubes will be in channels 0,2,4,6,etc. and the bottom in
> > channels 1,3,5,7,etc. Because there are 56 tubes per sector, and the
> > ribbon cable comes in groups of 16, we will only use 14 signals per
> > cable.
> >
> > I hope this is not an insurmountable problem, since otherwise the
> > module will be much larger, with lots of crossed wires on the pc board.
> > Please let me know if you have concerns or objections.
> >
> > Karen
> >
>
>
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