4. STRUCTURE OF PROTONS, NEUTRONS, AND MESONS
There are
some ways in which finding out what's inside a proton or neutron is analogous
to finding out what's inside the nucleus of an atom: fire probing particles
(say, electrons) of known energy at the nucleus, and look at the energy and
angle of the scattered particles - a standard sort of "fluoroscopy by
bombardment" technique. The electromagnetic
interaction between the charge of the probe and the charge distribution of the
nucleus will reveal how the target charges are arranged. If the probe energy is high enough, the
target will disintegrate, and the fragments, their energies, and their angles,
can be analyzed for clues to the composition and structure of the target.
In many
ways, however, the story isn't quite so simple when it comes to nucleons and
mesons. As the distance scale being probed decreases (with increasing probe
energy), the fluoroscopy "evolves" in a way different from that of
the atomic nucleus.
When a
nucleon is probed at the greatest distance scale, it responds as a single
object. At shorter lengths (higher probe energies), the momentum distribution
of the three valence quarks is revealed and some of the momentum of the nucleon
is observed to reside in the quanta of the color force, the gluons. At the smallest distance scales (highest
probe energies), still more momentum carriers manifest themselves – a sea of
quark-antiquark pairs coupled directly to the gluons. The momentum distributions of these constituent particles
(valence quarks, sea quarks and antiquarks, and gluons, collectively called
partons) are called the parton distribution functions. They are derived from
the interaction probability (the cross-section) of the probe lepton as a
function of energy and angle.
The parton
distribution functions parameterize the input hadron structure distributions in
the strong interaction description of lepton-hadron and hadron-hadron
interactions. As such, they may also be
investigated by studying the dynamics of many processes; e.g., single
hard-photon production at high transverse momentum, the production of high-mass
pairs of muons, and the production of heavy quarks. To the extent that these other processes are described by the
same distribution functions, QCD is providing a reliable description of strong
interactions. These other processes can then also be incorporated in the global
fits to produce a better determined set of distribution functions. While most
of the relevant measurements appear in experiments in this chapter, others can
be found in Sections 3 and 5.
The
universality of the parton distribution functions provides evidence for the
reality of partons, objects which have never been observed in isolation (QCD
predicts that this can never happen).
The parton distribution functions form the backbone of our understanding
of partons, and provide the basis for the predictive power of the Standard
Model (and the base for searches for new phenomena that lie outside the
Standard Model).
4.2 E605 - Leptons and Hadrons Near the
Kinematic Limits
CERN (Switzerland), Columbia, Fermilab,
KEK (Japan),
Kyoto (Japan), Saclay (France),
SUNY/Stony Brook, Washington
This
experiment was designed to measure energetic electrons, muons, pions, kaons,
and protons produced at large angles in the collision of 800 GeV protons with
protons and neutrons in nuclei. The production of particles at large angles
probes the quark, antiquark, and gluon structure of the proton and neutron much
as the original Rutherfoord scattering experiment probed the structure of the
atom.
E605
measured the production of massive muon pairs produced by the Drell-Yan
mechanism - the annihilation of a quark and antiquark into a virtual photon
which then decays to a muon pair. The
measured muon pair yields from E605 are one of the important experimental
inputs to perturbative QCD fits that yield the detailed momentum distribution
of the quarks, antiquarks and gluons in the proton. E605 also measured the yield of pions, kaons and protons at large
angles from nuclear targets with the aid of the large angular acceptance
ring-imaging cerenkov counter (RICH).
The ratios of the yields of these particles become constant at high
transverse momenta, independent of momentum and target Z, as is expected in a
QCD-parton description of particle production.
E605 Degree Recipients
George Coutrakon Ph.D. State University of New York at
Stony Brook
Jim Crittenden Ph.D. Columbia University
Henry Glass Ph.D. State University of New York at
Stony Brook
Richard Gray Ph.D. University of Washington
Yee-Bob Hsiung Ph.D. Columbia University
Dave Jaffe Ph.D. State University of New York at
Stony Brook
Gerardo Moreno Ph.D. Cinvestav
Anna Peisert Ph.D. University of Geneva
Bob Plaag Ph.D. University of Washington
Yoshi Sakai Ph.D. Kyoto University
Bruce Straub Ph.D. University of Washington
Takuo Yoshida Ph.D. Kyoto University
E605 Publications
A-Dependence of the Production of
Hadrons with High Transverse Momenta., Y.B. Hsiung, et al.,
Phys. Rev. Lett. 55, 457 (1985).
Inclusive Hadronic Production Cross Sections Measured in
Proton-Nucleus Collisions at Ö s = 27.4 GeV., J.A. Crittenden, et al., Phys. Rev. D34, 2584(1986).
A New Limit on Axion Production in
800 GeV Hadronic Showers.,
C.N. Brown et al., Phys. Rev. Lett. 57, 2101 (1986).
High-Transverse-Momentum
Hadron-Hadron Correlations in Ö s
= 38.8 GeV Proton-Proton Interactions., D.E. Jaffe, et al.,
Phys. Rev. D38, 1016 (1988).
High-Transverse-Momentum
Single-Hadron Production in pp and pd Collisions Ö
s = 27.4 and 38.8 GeV., D.E. Jaffe, et al., Phys. Rev. D40,
2777 (1989).
High Resolution Measurement of
Massive-Dielectron Production in 800-GeV Proton-Beryllium Collisions., T. Yoshida, et al., Phys. Rev. D39,
3516 (1989).
Dimuon Production in 800 GeV
Proton-Nucleus Collisions.,
C.N. Brown, et al., Phys. Rev. Lett. 63, 2637 (1989).
Dimuon Production in Proton-Copper Collisions at Ö
s = 38.8 GeV., G.
Moreno, et al., Phys. Rev. D43, 2815 (1991).
Nuclear Dependence of High-Xt Hadron and High-t Hadron Pair Production in p-A
Interactions at Ö
s = 38.8 GeV., P.B. Straub, et al., Phys. Rev. Lett. 68,
452 (1992).
Particle Ratios of
High-Xt Hadrons in p-A Interactions at Ö s
= 38.8 GeV., P.B.
Straub, et al., Phys. Rev. D45, 3030 (1992).
Nuclear Dependence of Single-Hadron
and DiHadron Production In p-A Interactions at Ö s = 38.8 GeV,. C.N. Brown, et al.,
Phys. Rev. C54, 3195 (1996).
4.3
E615
- forward production of muon pairs
University of Chicago, Fermi National
Accelerator Laboratory, Iowa State University, Princeton University
This experiment studied the quark structure of the p meson, using the Drell-Yan process of m+m- pair creation via a virtual photon in p-nucleus collisions. The data from E615 demonstrated that the momentum distribution of the valence quarks inside the pion extends to much larger fraction x of the pion's total momentum than is the case for quarks inside a proton or neutron. Also, it revealed a pattern of scaling violation in the quark distributions of the pion that is predicted by higher order scattering diagrams in QCD, known as a "higher twist effect".
E615 Degree Recipients
John Conway Ph.D. University of Chicago
E615 Publications
Measurement of the ratio of sea to valence quarks in the nucleon., J.G. Heinrich, et al., Phys. Rev. Lett. 63, 356 (1989).
Experimental study of muon pairs produced by 252 GeV pions on tungsten., J.S. Conway, et al., Phys. Rev. D39, 92 (1989).
Higher-twist effects in the reaction p+N ® µ+µ-X at 253 GeV/c., J.G. Heinrich, et al., Phys. Rev. D44, 1909 (1991).
4.4
E665
- Muon Scattering with Hadron Detection
ANL, UC/San Diego, Fermilab, Freiburg
(Germany), Harvard,Illinois/Chicago,
INP/Krakow (Poland), LLNL, Maryland, MIT,Max-Planck (Germany),
Northwestern, Ohio,
Pennsylvania, Washington, Wuppertal (Germany), Yale
Experiment E665 studied proton and nuclear structure using a high energy muon beam. Protons and neutrons are composed of partons; about half the momentum of a proton is carried by charged spin-1/2 quarks and the rest by neutral spin-1 gluons. Protons contain 3 valence quarks, which determine the quantum numbers of the proton, such as charge. However, in high energy experiments, protons also are observed to contain large numbers of force carriers (the gluons) and quark-antiquark pairs. The fraction of the proton or neutron momentum carried by a given quark can be measured by the recoil of a muon that interacts with that quark. The fraction is denoted by 'x'. The exact distribution of parton x between the valence quarks and the remaining quark antiquark pairs and gluons cannot yet be predicted from first principles, but the way in which such distributions change as the resolution of the probe (the inverse momentum transfer – 1/Q) varies, can be predicted by the theory of strong interactions Quantum Chromodynamics (QCD). The resolution dependence of proton structure scales with the logarithm of the momentum transferred by the probe, while the total rate for scattering can vary as a large power of the momentum transfer. As a result, precision measurements of large data samples are needed to disentangle the subtle logarithmic QCD effects from larger kinematic variations.
The E665 experiment was a continuation of both E98, an earlier Fermilab muon scattering experiment, which pioneered most of the techniques used in E665, and the EMC experiments at CERN. The Tevatron offered much higher beam energies and an improved beam with minimal halo. The E665 detector consisted of interchangeable hydrogen, deuterium, carbon, calcium, xenon and lead targets, high precision tracking chambers, electromagnetic calorimetry, and a final muon detector. The spectrometer had two magnets, one from the EMC experiment and one from E98. During the 1987 run, the vertex detector was a photographic streamer chamber from CERN experiment NA9, that yielded crucial information on the target fragmentation region for a subsample of the data.
Muon scattered in a range of angles as low as 1 mr, were detected and reconstructed. The high accuracy and large angular acceptance of the detector led to both absolute measurements of the proton and deuteron structure functions, and to precise measurements of the modifications of the parton distributions of nucleons bound in nuclei. These measurements covered the gap between the previous fixed target experiments and the HERA experiments H1 and Zeus, allowing determin-ation of the proton structure over a very large range of x and Q2 values. Because E665 had wide solid angle coverage, other aspects of the interaction were also studied, notably the relations between 'shadowing' (the decrease of low momentum parton probabilities in heavy nuclei) and the presence or absence of diffractive interactions.
E665 Degree Recipients
Silhacene Aid Ph.D. University of Maryland
P. Anthony Ph.D. Massachusetts Institute of
Technology
M. Baker Ph.D. Massachusetts Institute of
Technology
Arijit Banerjee Ph.D. University of Pennsylvania
Anwar Ahmad Bhatti Ph.D. University of Washington
T. Carroll Ph.D. University of Illinois at Chicago
Circle
H. Clark Ph.D. Ohio State University
Janet Marie Conrad Ph.D. Harvard University
William Michael Dougherty Ph.D. University of Washington
U. Ecker Ph.D. Wuppertal University
M. Erdmann Ph.D. University of Freiberg
Rurngsheng Guo-Sheng Ph.D. University of Illinois at Chicago
Circle
D. Hantke Ph.D. Technischen Universitaat Munich
Douglas Maurice Jansen Ph.D. University of Washington
Zhong Jin Ph.D. University of Washington
Robert D. Kennedy Ph.D. University of California at Davis
Ashutosh Vijay Kotwal Ph.D. Harvard University
Patrick Madden Ph.D. University of California at San
Diego
Stephen R. Magill Ph.D. University of Illinois at Chicago
Circle
Douglas Grant Michael Ph.D. Harvard University
Stephen Charles O'Day Ph.D. University of Maryland
Erik Joel Ramberg Ph.D. University of Maryland
J. Ryan Ph.D. Massachusetts Institute of
Technology
Alexandro F. Salvarani Ph.D. University of California at Davis
Michael Henry Schmitt Ph.D. Harvard University
S. Soeldner-Rembold Ph.D. Technischen Universitaat Munich
Panagiotis Spentzouris Ph.D. Northwestern University
M. Wilhelm Ph.D. University of Freiberg
Proton and
deuteron structure functions in muon scattering at 470 GeV., M.R. Adams, et al.,
Phys. Rev. D54, 3006 (1996).
Shadowing in inelastic scattering of muons on carbon, calcium and lead at low xBj., M.R. Adams, et al., Z. Phys. C67, 403 (1995).
Extraction
of the ratio F2(n)/F2(p)
from muon-deuteron and muon-proton scattering at small x and Q2.,
M.R. Adams, et al., Phys. Rev. Lett. 75, 1466 (1995).
First
measurements of jet production rates in deep inelastic lepton - proton
scattering., M.R. Adams, et al.,
Phys. Rev. Lett. 69, 1026 (1992).
Saturation of shadowing at very low xBj., M.R. Adams, et al., Phys. Rev. Lett. 68, 3266 (1992).
Inclusive single-particle distributions and transverse momenta of forward produced charged hadrons in mu p scattering at 470 GeV., M.R. Adams, et al., Z. Phys. C76, 441 (1997).
Diffractive
production of r o(770) mesons in muon-proton
interactions at 470 GeV., M.R. Adams, et
al., Z. Phys.C74, 237 (1997).
Proton and deuteron structure functions in muon scattering at 470 GeV., M.R. Adams, et al., Phys. Rev. D54, 3006 (1996).
Determination of the gluon distribution function of the nucleon using energy-energy angular pattern in deep inelastic muon-deuteron scattering., M.R. Adams, et al., Z. Phys. C71, 391 (1996).
Nuclear decay following deep inelastic scattering of 470 GeV muons., M.R. Adams, et al., Phys. Rev. Lett. 74, 5198 (1995), Erratum-ibid. 80, 2020 (1998).
Shadowing in inelastic scattering of muons on carbon, calcium and lead at low xBj., M.R. Adams, et al., Z. Phys. C67, 403 (1995).
Extraction of the ratio F2(n)/F2(p) from muon - deuteron and muon - proton scattering at small x and Q2., M.R. Adams, et al., Phys. Rev. Lett. 75, 1466 (1995).
Measurement of nuclear transparencies from exclusive r o meson production in muon-nucleus scattering at 470 GeV., M.R. Adams, et al., Phys. Rev. Lett. 74, 1525 (1995).
Nuclear shadowing, diffractive scattering and low momentum protons in m Xe interactions at 490 GeV., M.R. Adams, et al., Z. Phys. C65, 225 (1995).
Density and
correlation integrals in deep inelastic muon-nucleon scattering at 490 GeV., M.R. Adams, et al., Phys. Lett. B335,
535 (1994).
Scaled energy (z) distributions of charged hadrons observed in deep inelastic muon scattering at 490-GeV from xenon and deuterium targets. M.R. Adams, et al., Phys. Rev. D50, 1836 (1994).
Production of charged hadrons by positive muons on deuterium and xenon at 490 GeV., M.R. Adams, et al., Z. Phys. C61, 179 (1994).
Q2 dependence of the average squared transverse energy of jets in deep inelastic muon-nucleon scattering with comparison to QCD., M.R. Adams, et al., Phys. Rev. Lett.72, 466 (1994).
Production of neutral strange particles in muon-nucleon scattering at 490 GeV., M.R. Adams, et al., Z. Phys. C61, 539 (1994).
Perturbative QCD effects observed in 490 GeV deep inelastic muon scattering., M.R. Adams, et al., Phys. Rev. D48, 5057 (1993).
An Investigation of Bose-Einstein correlations in muon-nucleon interactions at 490 GeV., M.R. Adams, et al., Phys. Lett. B308, 418 (1993).
Measurement of the ratio s(n)/s (p) in inelastic muon-nucleon scattering at very low x and Q2., M.R. Adams, et al., Phys. Lett. B309, 477 (1993).
Shadowing in
the muon xenon inelastic scattering cross-section at 490 GeV., M.R. Adams, et al., Phys. Lett. B287,
375 (1992).
First measurements of jet production rates in deep inelastic lepton-proton scattering., M.R. Adams, et al., Phys. Rev. Lett. 69, 1026 (1992).
Saturation of shadowing at very low xBj.,, M.R. Adams, et al., Phys. Rev. Lett. 68, 3269 (1992).
Distributions of charged hadrons observed in deep inelastic muon - deuterium scattering at 490 GeV., M.R. Adams, et al., Phys. Lett. B272, 163 (1991).
4.5 E733 - High Energy Neutrino Interactions
with the Tevatron Quadrupole Triplet Beam
Fermilab, Florida, MIT, Michigan State
This experiment was designed as a follow-on to E-594 and to act as a "first look" at high energy neutrino collisions from the first wide band beams at the Tevatron. The detector for this experiment was the 300 ton Flash-Chamber Proportional-Tube Calorimeter in Lab C constructed by the Fermilab, MIT, Michigan State Collaboration. The primary feature of this detector was the fine-grain sampling that allowed for the measurement of the direction of hadron showers. Shower energy at the Tevatron was determined by measuring the pulse height in the proportional tubes, and muon momenta were determined by large drift planes that were in the 12 ft. and 24 ft. toroidal magnets downstream of the calorimeter.
The original physics interest in this new regime (beyond the establishment of well-known behavior such as scaling), involved a variety of reactions which were hinted at in lower energy experiments as well as searching for new phenomena. The primary measurements involved determination of opposite sign dimuon final states, limits on weakly interacting massive particles, and detailed shower shapes.
E733 Degree Recipients
William Gilbert Cobau Ph.D. Michigan State University
Elizabeth Jean Gallas Ph.D. Michigan State University
Robert William Hatcher Ph.D. Michigan State University
George John Perkins Ph.D. Michigan State University
Boris Strongin Ph.D. Massachusetts Institute of
Technology
E733 Publications
Study of Opposite-sign Dimuon Production in High Energy Neutrino Nucleon Interactions., B. Strongin, et al., Phys. Rev. D43, 2778 (1991).
A Search for Weakly Interacting Massive Particles (WIMPS) in the Tevatron Wide Band Neutrino Beam., S. Gallas, et al., Phys. Rev. D52, 6 (1995).
4.6 E744/770
- Neutrino Physics at the Tevatron
Chicago, Columbia, Fermilab, Rochester,
Wisconsin
In 1983, a major threat to the Standard Model of particle physics was the observation of same-sign dimuons, two muons of the same sign, produced in neutrino interactions in unexpectedly large numbers and at a rate that rose with energy. The high-energy, high-intensity neutrino beam from the Tevatron provided physicists on E744 with the opportunity to examine this anomaly. While this investigation was a primary goal (and E744's analysis showed that the behavior of this process did in fact agree with the Standard Model), it was far from the experiment's only purpose.
E744 (which ran in 1985) and its immediate successor, E770 (1987-88), set forth to perform a high-statistics, high-energy measurement of the neutrino cross sections; to extract nucleon structure functions (fundamental distributions describing weak interactions on nuclear matter) and the distributions of quark momenta in nucleons; and to test the theory of the strong interaction, Quantum Chromodynamics (QCD), by looking at opposite-sign dimuons and measuring the strong interaction coupling constant. These measurements were accomplished by operating the wide-band neutrino beam, generated by targeting the Tevatron proton beam onto a block of beryllium oxide, and magnetically focusing the secondary charged particles through a long beam tube (aimed at the detector), where they decayed into an intense mixed beam of energetic neutrinos and antineutrinos. The physicists used the Lab E detector, an instrumented iron target calorimeter (to measure particle position and energy) followed by a magnetic spectrometer (to determine the momentum of penetrating muons). The calorimeter utilized sandwiched scintillation counters and drift chambers, between ten-foot-square, two-inch-thick plates of steel, to form a 690-ton detector nearly sixty feet in length.
By 1992, the Standard Model was in such good shape that precision measurements of its fundamental parameters (such as the weak mixing angle, which describes how the weak and electromagentic forces unite) could signal new physics. Improvements in collider experiments meant that the value of this mixing angle, measured first in neutrino scattering, could now be determined by means of several extremely different processes. Once again, neutrino scattering could put the Standard Model to a stringent test. However, achieving this improvement required the use of a new technique, employing separate neutrino and antineutrino beams. Measuring the weak mixing angle using these separate beams was a major goal of a future experiment, E815 described in Section 7.
E744/770 Degree Recipients
Carlos Gerardo Arroyo Ph.D. Columbia University
Kurt Bachmann Ph.D. Columbia University
Pawel de Barbaro Ph.D. University of Rochester
Andrew Orest Bazarko Ph.D. Columbia University
Costas Foudas Ph.D. Columbia University
John Kim Ph.D. Columbia University
Bruce King Ph.D. Columbia University
Timothy Kinnel Ph.D. University of Wisconsin
Walter Lefmann Ph.D. Columbia University
Wing Cheong Leung Ph.D. Columbia University
Cynthia Kay McNulty Ph.D. Columbia University
Paul Quintas Ph.D. Columbia University
Steve Rabinowitz Ph.D. Columbia University
Alexandru Romosan Ph.D. Columbia University
Pamela Helen Sandler Ph.D. University of Wisconsin
Bruce A. Schumm Ph.D. University of Chicago
Masoud Vakili Ph.D. University of Cincinnati
E744/E770 Publications
A Search for Neutral Heavy Leptons in Neutrino-N Interactions., S.R. Mishra, et al., Phys. Rev. Lett. 59, 1397 (1987).
Neutrino Production of Same Sign Dimuons., B.A. Schumm, et al., Phys. Rev. Lett. 60, 1618 (1988).
Study of Wrong-Sign Single Muon Production in Neutrino–Nucleon Interactions., S. Mishra, et al., Z. Phys. C 44, 187 (1989).
Inverse Muon Decay and Neutrino Dimuon Production at the Tevatron., S.R. Mishra, et al., Phys. Rev. Lett. 63, 132 (1989).
Hadron Shower Penetration Depth and Muon Production by Hadrons of 40, 70, and 100 GeV., P.H. Sandler, et al., Phys. Rev. D42, 759 (1990).
Neutrino Production of Opposite Sign Dimuons at TeV Energies., C. Foudas, et al., Phys. Rev. Lett. 64, 1207 (1990).
Inverse muon decay, nm + e ® m + ne , at the Fermilab Tevatron., S.R. Mishra, et al., Phys. Lett. B252, 170 (1990).
Neutrino
Tridents and W-Z Interference., S. Mishra, et al., Phys. Rev. Lett. 66,
3117 (1991).
A
Measurement of TeV Muon Energy Loss in Iron., W.K. Sakumoto, et al., Phys. Rev. D45, 3042 (1992).
Search for Right-Handed Couplings in Neutrino-N Scattering., S. Mishra, et al., Phys. Rev. Lett. 68 , 3499 (1992).
A Measurement of the Gross-Llewellyn Smith Sum Rule from the CCFR xF3 Structure Function., W.C. Leung, et al., Phys. Lett. B317, 655 (1993).
Measurement of LQCD from Neutrino-Fe Nonsinglet Structure Functions at the Fermilab Tevatron., P.Z. Quintas, et al., Phys. Rev. Lett. 71, 1307 (1993).
Measurement of the Strange Sea Distribution Using Neutrino Charm Production., S.A. Rabinowitz, et al., Phys. Rev. Lett. 70, 134 (1993).
Neutrino Production of Same Sign Dimuons at the Fermilab Tevatron., P.H. Sandler, et al., Z. Phys. C57, 1 (1993).
A Precise Measurement of the Weak Mixing Angle in Neutrino Nucleon Scattering., C.G. Arroyo, et al., Phys. Rev. Lett. 72, 3452 (1994).
A
Determination of the Strange Quark Content of the Nucleon from a
Next-to-Leading-Order QCD Analysis of Neutrino Charm Production., A.O.
Bazarko, et al., Z. Phys. C65, 189 (1994).
Limits on nm ® nt and nm ® ne Oscillations from a Precision Measurement of Neutrino-Nucleon Neutral Current Interactions., K.S. McFarland, et al. , Phys. Rev. Lett. 75, 3993 (1995).
Tests of a Calorimetric Technique for Measuring the Energy of Cosmic Ray Muons in the TeV Energy Range., A.P. Chikkatur, et al., Z. Phys. C74 (1997) 279.
Improved Determination of as from Neutrino Nucleon Scattering., W.G. Seligman, et al., Phys. Rev. Lett.79 , 1213 (1997).
A High Statistics Search for Muon-Neutrino (Anti-neutrino) to Electron-Neutrino (Anti-neutrino) Oscillations in the Small Mixing Angle Regime., A. Romosan, et al., Phys. Rev. Lett.78, 2912 (1997).
A measurement of as(Q2) from the Gross-Llewellyn Smith sum rule., J.H. Kim, et al., Phys. Rev. Lett. 81, 3595 (1998).
A high statistics search for nm ® nt oscillations., D. Naples et al., Phys. Rev D59, 031101 (1999).
Nuclear Structure Functions in the Large x Large Q2 Kinematic Region in Neutrino Deep Inelastic Scattering., M. Vakili, et al., Phys. Rev. D61, 52003 (2000).
4.7 E745/782 - the tohoku high-resolution
bubble chamber
Brown, Fermilab, IHEP/Beijing (PRC),
MIT, ORNL, Sensyu (Japan), Sugiyama Jogakuin (Japan), Tennessee,Tohoku Gakuin
(Japan), Tohoku (Japan)
E-745 was a muon-neutrino experiment using the Tohoku high-resolution one-meter freon bubble chamber. High spatial resolution of 70 mm was obtained with holographic optics. The physics aims were: (1) studies of neutrino interactions in the high Q2 region, (2) studies of charm and heavy quarks, and (3) new phenomena, e.g. tau neutrino events. During the 1985 and 1987 fixed target runs, 200,000 and 360,000 pictures were taken, respectively.
E-782 was a muon exposure in the Tohoku High-Resolution One-Meter Freon Bubble Chamber. Unique features of this experiment were the observation of vertices with high- resolution optics, and low Q2 data with small systematic bias. The analysis included 8163 events above En = 1 GeV.
E-745 Degree
Recipients
K. Furuno, Ph. D Tohoku University.
J. Harton, Ph. D. MIT.
J. Shimony, Ph. D. University of Tennessee.
K. De, Ph. D. Brown University.
H. Suzuki, Ms Tohoku University.
M. Sasaki, Ph. D. Tohoku University.
H. Kawamoto, Ms Tohoku University.
E745 Publications
A New Method to Investigate the Nuclear Effect in Leptonic Interactions., T. Kitagaki, et al., Phys. Lett. B214, 281 (1988).
E782 Degree Recipients
James Allen Stewart Ph.D. University of Michigan
4.8 E866 -
Measurement of anti-d(x)/anti-u(x) in the Proton
Abilene Christian, ANL, Fermilab,
Georgia State, IIT, LANL,
Louisiana, New Mexico State, New Mexico,
ORNL, Texas A&M, Valparaiso
E-866 (NuSea) made a precision measurement of the yield of oppositely charged pairs of muons (with masses between 6-9 GeV and 11-15 GeV, so called Drell-Yan dimuons) from protons incident on hydrogen and deuterium targets. According to the QCD description of muon pair production, the Drell-Yan dimuon yield is directly proportional to the antiquark composition of the nucleon. The E866 results greatly improve the experimental knowledge of the ratio of d-antiquark to u-antiquark in the proton versus, the fractional antiquark momentum, designated ‘x’. The observed asymmetry of d-antiquark to u-antiquark has resulted in newer parameterizations of the distribution of quarks and antiquarks in the nucleon. Bound state non-perturbative effects, such as virtual meson formation, are thought to be the source of the observed asymmetries.
In addition, E866 made measurements of the Drell-Yan, J/y, y', and upsilon yields, and angular distributions from nuclear targets over broad ranges in xF and pT. The yield and polarization of these states can be compared with theoretical predictions.
E866 Degree Recipients
T. Chang Ph.D. New Mexico State University
W.M. Lee Ph.D. Georgia State University
R.S. Towell Ph.D. University of Texas at Austin
J.C. Webb Ph.D. New Mexico State University
E866 Publications
Measurement of the Light Antiquark Flavor Asymmetry in the Nucleon Sea., E.A. Hawker, et al., Phys. Rev. Lett. 80, 3715 (1998).
/Asymmetry and the Origin of the Nucleon Sea ., J.C. Peng, et al., Phys. Rev. D58, 92004 (1998).
Parton Energy Loss Limits and Shadowing in Drell-Yan Dimuon Production., M.A. Vasiliev, et al., Phys. Rev. Lett. 83, 2304 (1999).
Measurement of Differences between J/y and y ' Suppression in p-A Collisions., M.J. Leitch, et al., Phys. Rev. Lett. 84, 3256 (2000).
