Hi,
for the sake of having a good check of misidentified proton events and
their asymmetry at the same target spin angle like in D2 running, Vitaliy
has requested some 40kC of hydrogen data under the same conditions.
This means 7-10 days of running at 32 degrees.
Given that the uncertainties in GEp/GMp and E2/M1 compete with each other
on the order of 20-25% for the two spin angles, I would rather recommend
to then continue at 45 degrees since the approved proposals should define
the preferences.
Regards,
Michael
>
> Hello John,
> in a subsequent email chris has shown that with the - by now - known (and
> equal) hydrogen vector polarizations at 32 and 45 deg spin angle the Ge/Gm
> error improves by a factor of 0.73 - 0.83. Me and chris have just run a
> similar analysis for N-Delta.
>
> The 2 asymmetries there can be used to extract Rtt' (spin parallel kin,
> \propto M1) and Rlt' terms (spin perp, \propto E2,C2). Spin parallel and
> perp take a different meaning here because the q-direction is forward
> (experience says 30 deg). So with help from MAID partial cross section the
> error propagation goes like this (in a.u.)
>
> spin 32 deg: delta_Alt' ~ 10.0 delta_Att' ~ 13.1
>
> spin 45 deg: delta_Alt' ~ 12.2 delta_Att' ~ 8.5
>
> clearly at 32 deg one would hope for a better measurement of the E2,C2
> terms by about 20 %. This is way 32 deg is preferrable - i think - for
> N-delta.
>
> As a collaboration we said we were going to discuss this, and here are
> the numbers. I am sure richard could help here.
>
> We are now measuring at 32 deg only for the sake of measuring the
> same asymmetries and in the same set-up as for the D2 run (as you know
> the 32 deg proton asymmetry is important for d2).
>
> regards
> -- tancredi
>
> ________________________________________________________________________________
> Tancredi Botto, phone: +1-617-253-9204 mobile: +1-978-490-4124
> research scientist MIT/Bates, 21 Manning Av Middleton MA, 01949
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>
> On Sun, 31 Oct 2004, John Calarco wrote:
>
> >
> > Hi Tancredi,
> >
> > Chris has shown that the target polarization at 45 deg is as at least
> > as good as at 32 deg. As one of the spokespersons for the hydrogen
> program
> > I request that we continue at 45 deg.
> >
> > John
> >
> >
> >
> >
> > On Sun, 31 Oct 2004, Electronic Log Book wrote:
> >
> > > Operator: tancredi
> > >
> > > Continued ABS data but as ABS was losing intensitiy very rapidly (see
> > > http://blast02.lns.mit.edu/elog/2004/10/31/30644.html ) decided to switch to
> > > empty at around 10 am and started cycling nozzle.
> > >
> > > Lost about 2 hours due to network problems. Hopefully they had been solved
> > > now that barbara idenitifed a troublesome network switch. Tried to take
> > > data in the meantime but roc got disconnected and could not reboot until
> > > network came back
> > >
> > > Now genya is starting He3 program. Plan is to go back to 32 deg hydrogen
> > > for the night
> > >
> > >
> > >
> >
> >
>
>
>
--+-------------------------------------+--------------------------+ | Office: | Home: | |-------------------------------------|--------------------------| | Dr. Michael Kohl | Michael Kohl | | Laboratory for Nuclear Science | 5 Ibbetson Street | | MIT-Bates Linear Accelerator Center | Somerville, MA 02143 | | Middleton, MA 01949 | U.S.A. | | U.S.A. | | | - - - - - - - - - - - - | - - - - - - - - -| | Email: kohlm@mit.edu | K.Michael.Kohl@gmx.de | | Work: +1-617-253-9207 | Home: +1-617-629-3147 | | Fax: +1-617-253-9599 | Mobile: +1-978-580-4190 | | http://blast.lns.mit.edu | | +-------------------------------------+--------------------------+
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