RadPhi Experiment at William & Mary
Hadronic Physics
Group
(Armstrong, Steiner, Roche)
The Radiative Phi Decay Experiment
(aka `RadPhi', E94-016) in
Hall B at Jefferson Lab, is in
the field of meson spectroscopy, the study of the structure and systematics
of mesons (quark-antiquark bound states), and the search for exotic
strongly-interacting particles allowed by QCD, such as glueballs, mesonic molecules
and 4-quark states.
In particular, the experiment seeks to measure certain rare radiative
decay modes of the phi meson, with the primary
goal of elucidating the structure of the f0(975) and a0(980) states. These two scalar
(JPC = 0++) states
are possible candidates as 4-quark bags, K-Kbar molecules, or even, in the case of the
f0, of being the lightest
glueball. The scalar meson nonet is oversubscribed, with several
`extra' light f0 states
listed by the Particle Data Group. Since the quark structure of the
phi(1020) is well known (it is an almost pure
s-sbar state), the branching ratio for its
radiative decays into the f0
and a0 is readily calculable
given different assumptions about the structure of these later two
states.
Other decays studied or searched for in this experiment include phi -> eta' gamma (useful for studying the gluonic
and s-sbar content of the eta'), phi -> omega
pi0 (a yet-to-be observed isospin-violating
decay), phi -> omega gamma (which would be
C-violating), and a0 -> omega
gamma (which yields similar information to phi -> a0 gamma).
RadPhi took engineering and commissioning data in the summers of 1998
and 1999, and the final production data-taking took place in May-July
2000. Initial analysis indicates a copious supply of all-neutral
phi-decay events, and the ability to reconstruct multi-photon final
states. Our group has contributed to online and offline software
development, data analysis, as well as some hardware tasks (DAQ, PMT
testing, construction of a pair-veto detector), and a large number of
shifts on the experiment. This project has been a particularly rich
avenue for student training: five senior theses (Alex Dubanowitz, Adam Gurson,
Lisa Kaufman, Tom O'Connor, Eric Koskinen) have been completed on different aspects of the
experiment; several other
undergraduate or graduate students participated in data-taking and
software development (Mandy Brown, Caroline Cheze, Jessica Clark,
Jennifer Knowles, Allyn Powell, Sandy Sligh),
and graduate student Dan Steiner will base his PhD thesis on analysis
of these data.
RadPhi Links:
Back to the Hadronic Physics Group
Hadronic Physics Group
Physics Department
Graduate Studies in Physics at
William and Mary
Jefferson Lab
armd@physics.wm.edu
last updated: June 3 2002