BONuS experiment status update.

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BONuS experiment status update.

• S.Tkachenko,
• Old Dominion University
• for BONuS collaboration.

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Outline

• Reminder of what BONuS is.
• Current status.

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Spectator Tagging
E 4.223 GeV
ltQ2gt 1.19 (GeV/c)2

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Spectator Tagging (contd)

• Low momentum spectators
• 70 lt PS lt 100 MeV/c
• Backward kinematics
• ?qp gt 110o
• Rescattering of proton by deep
• inelastic remnants O (5)?
• correction

• Minimize uncertainty due to
• d wave function and on-shell
• extrapolation
• O (1) correction
• Minimize effects from
• final state interactions
• and target fragmentation
• Production of low-energy protons by
• hadronic debris of struck nucleon
• totally negligible

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The CLAS with the RTPC and one electron event.
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BONUS RTPC Design
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p- Production Kinematics
g n -gt p- p
p-
??,k?
f
q2 -Q2 4??? sin2(qe/2) w? 2 (qµ PDµ -
Psµ)2 q angle between the emitted and the
virtual photon in C.M. f angle between the
leptonic and hadronic planes
q
w,q
n
?,k
p
Leptonic plane
Hadronic plane
Exclusive virtual photon cross-section
Where the response functions Ri(Q2,W?,q) are
bilinear combination of the helicity amplitudes
? and ?L are defined as
Jixie Zhang, DNP2008
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Missing Mass, E 5.3GeV, No acceptance
correction yet
Require e? and p- be detected by CLAS. Top right
One proton was detected by CLAS Bottom left
One proton was detected by the RTPC Bottom
right Protons have been detected in both the
RTPC and CLAS. The purple area is under the
proton mass cut from 0.838 to 1.038 GeV
Jixie Zhang, DNP2008
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Structure function ratio.
PRELIMINARY
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Yield ratio as a function of W.
PRELIMINARY
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Yield corrected for CLAS, RTPC efficiency.
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Model used to correct for CLAS efficiency.
Inclusive CLAS data (black) overlaid with model
for electron-deuteron scattering (red), scaled.
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Conclusions

• Preliminary analysis is done.
• Simulations are done.
• Physics analysis is underway