Although we are running now with a restricted trigger, another project
would be to look for N-Delta protons (in older runs)
Even without a full set-up (CC, tracking) we can look for (e,e' p)pi0
in parallel kinematics, i.e. the proton is along q. This has to be
coplanar. Take f.i. 27 deg for the electron and 29 deg for theta_q. This
is about top of the resonance (W=1232, Q2=0.13 ..).
With the field on and the extended target the e- will bend in up to 1-2
tofs. The proton will bend outward by about the same amount. So one place
to look is f.i. tof 2-3 w/ tof 6-7.
However realize that our ADC>7000 cut is very good at backward angles were
protons have very low energy when they reach the TOF. There are some
estimates in the logbook. Proton momenta in the aobve kinematics will be
ca. 670 MeV/c, i.e. 210 MeV so your ADC cut should allow for less energy
loss. But nothing else should be coplanar in that region.
You can require CC=0, on the proton side. it does not tag uniquely a
proton (pion) but it will anyways help to get rid of ca 60% of "shower" events.
Note, for the same kinematics a pion+ collinear with q (from e,e'pi+n)
has 130 or 360 MeV/c momenta (backward, forward CM emission angle). It
will also be collinear and the q direction of course, does not change.
-t
________________________________________________________________________________
Tancredi Botto, phone: +1-617-253-9204 mobile: +1-978-490-4124
research scientist MIT/Bates, 21 Manning Av Middleton MA, 01949
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