-
UA Collaboration,
T. Åkesson,
J. Alitti,
R. Ansari,
R. E. Ansorge,
P. Bagnaia,
P. Bareyre,
G. Blaylock,
P. Bonamy,
M. Bonesini, [......],
S. N. Tovey,
G. Unal,
M. Valdata-Nappi,
V. Vercesi,
A. R. Weidberg,
P. S. Wells,
T. O. White,
D. R. Wood,
S. A. Wotton,
H. Zaccone
[show abstract]
[hide abstract]
ABSTRACT: The upgraded UA 2 detector has collected data corresponding to a total integrated luminosity of 7.5 pb–1 from
[`(p)]p\bar pp
collisions at a centre of mass energy of 630 GeV during 1988 and 1989. A search has been performed for the production and decay of the top quark (t) or a member of a hypothetical fourth family (b). No evidence has been found for such processes. Using the expected rates for production and decay branching ratios from the Standard Model, this implies that the top quark mass is greater than 69(71) GeV/c2, and that theb mass is greater than 54(57) GeV/c2, at 95(90)% confidence.
Zeitschrift für Physik C 05/1990; 46(2):179-189.
-
J. Alitti,
R. Ansari,
R. E. Ansorge,
P. Bagnaia,
P. Bareyre,
G. Blaylock,
P. Bonamy,
M. Bonesini,
C. N. Booth,
K. Borer, [......],
S. N. Tovey,
E. Tsesmelis,
M. Valdata-Nappi,
V. Vercesi,
A. R. Weidberg,
P. S. Wells,
T. O. White,
D. R. Wood,
S. A. Wotton,
H. Zaccone
[show abstract]
[hide abstract]
ABSTRACT: Results on the production cross sections ofW andZ bosons detected in the UA2 experiment are given based on a large sample ofWe andZe
+
e
– decays. The measured cross sections are
W
e
= 66015(stat)37(syst)pb,
Z
e
= 70.45.5(stat)4.0(syst)pb and their ratioR=9.38
–0.72
+0.82
(stat)0.25(syst). In the framework of the Standard Model, the measured value ofR is used to determine the total width of theW, (W)=2.300.19(stat)0.06(syst) GeV.
Zeitschrift für Physik C 02/1990; 47(1):11-22.
-
R. E. Ansorge,
B. Åsman,
L. Burow,
P. Carlson,
R. S. DeWolf,
B. Eckart,
G. Ekspong,
I. Evangelou,
C. Fuglesang,
J. Gaudaen, [......], J. G. Rushbrooke,
F. Triantis,
L. Van Hamme,
C. Walck,
C. P. Ward,
D. R. Ward,
C. J. S. Webber,
T. O. White,
G. Wilquet,
N. Yamdagni
[show abstract]
[hide abstract]
ABSTRACT: Multiplicity distributions of charged particles produced in non single-diffractive collisions between protons and antiprotons at centre of mass energies of 200 and 900 GeV are presented. The data were recorded in the UA5 streamer chambers at the CERN Collider, which was operated in a pulsed mode between the two energies. A new method to correct for acceptance limitations and inefficiencies based on the principle of maximum entropy has been used. Multiplicity distributions in full phase space and in intervals of pseudorapidity are presented in tabular form. The violation of KNO scaling in full phase space found by the UA5 group at an energy of 546 GeV is confirmed also at 200 and 900 GeV. The shape of the 900 GeV distribution in full phase space is narrower in the peak region than at 200 GeV but exhibits a pronounced high multiplicity tail. The negative binomial distribution fits data at 200 GeV in all pseudorapidity intervals and in small intervals at 900 GeV. In large intervals at 900 GeV, however, the negative binomial distribution. Fits to the partially coherent laser distribution are also presented as well as comparisons with predictions of the Dual Parton, the Fritiof and the Pythia models.
Zeitschrift für Physik C 08/1989; 43(3):357-374.
-
UA Collaboration,
R. E. Ansorge,
B. Åsman,
L. Burow,
P. Carlson,
R. S. De Wolf,
B. Eckart,
G. Ekspong,
C. Fuglesang,
J. Gaudaen, [......], J. G. Rushbrooke,
F. Triantis,
L. Van hamme,
C. Walck,
C. P. Ward,
D. R. Ward,
C. J. S. Webber,
T. O. White,
G. Wilquet,
N. Yamdagni
[show abstract]
[hide abstract]
ABSTRACT: We present data on photon production in non single-diffractivep
[`(p)]\bar p
-collisions at c.m. energies of 200 and 900 GeV. Besides the general properties of photon production, i.e. pseudorapidity
distribution and average multiplicity, we also investigate photon-charged two-particle pseudorapidity and multiplicity correlations.
We find for the average number of photons in non single-diffractivep
[`(p)]\bar p
-collisions 22.2±1.4±2.0 at 200 GeV and 41.4±2.1±3.5 at 900 GeV, where the first error is statistical and the second systematic.
The analysis of photon-charged particle multiplicity correlations reveals strong positive correlations between the average
number of photons and the number of simultaneously produced charged particles, as expected from FNAL and ISR studies and from
our result at 546 GeV. We obtain for the correlation slope 0.95±0.08±0.11 at 200 GeV and 1.09±0.09±0.13 at 900 GeV (first
error is statistical and the second systematic). The investigation of photon-charged two-particle pseudorapidity correlations
shows that these correlations are of short range and compatible with the observed charged two-particle pseudorapidity correlations.
These correlations and the results for the average number of photons as a function of the produced number of charged particles
favour the conclusion that photon sources other than π0
s contribute significantly to the observed photon yield in non single-diffractivep
[`(p)]\bar p
-collisions. For example, if all photons are assumed to come from π0
s and η mesons, a η/π0 ratio of about 20% is inferred.
Zeitschrift für Physik C 02/1989; 43(1):75-89.
-
R. E. Ansorge,
B. Åsman,
C. N. Booth,
L. Burow,
P. Carlson,
R. S. DeWolf,
B. Eckart,
G. Ekspong,
C. Fuglesang,
J. Gaudaen, [......],
H. Schmickler,
F. Triantis,
L. Van Hamme,
C. Walck,
C. P. Ward,
D. R. Ward,
C. J. S. Webber,
T. O. White,
G. Wilquet,
N. Yamdagni
[show abstract]
[hide abstract]
ABSTRACT: We present data on two-particle pseudorapidity and multiplicity correlations of charged particles for non single-diffractive
p[`(p)] - collisionsp\bar p - collisions
at c.m. energies of 200, 546 and 900 GeV. Pseudorapidity correlations interpreted in terms of a cluster model, which has been motivated by this and other experiments, require on average about two charged particles per cluster. The decay width of the clusters in pseudorapidity is approximately independent of multiplicity and of c.m. energy. The investigations of correlations in terms of pseudorapidity gaps confirm the picture of cluster production. The strength of forward-backward multiplicity correlations increases linearly with ins and depends strongly on position and size of the pseudorapidity gap separating the forward and backward interval. All our correlation studies can be understood in terms of a cluster model in which clusters contain on average about two charged particles, i.e. are of similar magnitude to earlier estimates from the ISR.
Zeitschrift für Physik C 05/1988; 37(2):191-213.
-
R. E. Ansorge,
B. Åsman,
C. N. Booth,
L. Burow,
P. Carlson,
R. S. De Wolf,
B. Eckart,
G. Ekspong,
C. Fuglesang,
J. Gaudaen, [......], J. G. Rushbrooke,
F. Triantis,
L. Van hamme,
C. Walck,
C. P. Ward,
D. R. Ward,
C. J. S. Webber,
T. O. White,
G. Wilquet,
N. Yamdagni
[show abstract]
[hide abstract]
ABSTRACT: A detailed analysis ofK
s
0
production in
[`(p)]p\bar pp
|K
s
0
production cross sections in inelastic collisions are 294 mb at 200 GeV and 636 mb at 900 GeV, showing an increase compared to lower energy data. The central kaon density is found to increase as a logarithmic function of energy. At 900 GeV, where statistics are sufficient to allow one to draw conclusions, the average transverse momentum is higher in events with large charged multiplicity than in events with low multiplicity.
Zeitschrift für Physik C 01/1988; 41(2):179-190.
-
G. J. Alner,
K. Alpgård,
P. Anderer,
R. E. Ansorge,
B. Åsman,
S. Berglund,
K. Berkelman,
D. Bertrand,
C. N. Booth,
C. Buffam, [......],
H. Schmickler,
F. Triantis,
L. van Hamme,
Ch. Walck,
C. P. Ward,
D. R. Ward,
G. Weber,
T. O. White,
G. Wilquet,
N. Yamdagni
Physics Reports 09/1987; 154:247-383. · 20.39 Impact Factor
-
R. E. Ansorge,
B. Åsman,
C. N. Booth,
L. Burow,
P. Carlson,
R. S. De Wolf,
A. Drees,
B. Eckart,
G. Ekspong,
I. Evangelou, [......],
H. Schmickler,
F. Triantis,
L. Van hamme,
C. Walck,
C. P. Ward,
D. R. Ward,
C. J. S. Webber,
T. O. White,
G. Wilquet,
N. Yamdagni
[show abstract]
[hide abstract]
ABSTRACT: Cross-sections for diffractive particle production and pseudorapidity distributions of the decay products of diffractive states are presented. The data were obtained with the UA 5 streamer chamber detector at the CERNpp Collider operated in a new pulsed mode yieldingpp interactions at c.m. energies of 900 and 200 GeV. Data recorded with a special trigger designed to select a sample of events enriched in single-diffractive interactions clearly favour ap
t
-limited fragmentation of diffractive states. The cross-section for single-diffractive particle production was found to be 7.80.51.1 mb at 900 GeV and 4.80.50.8 mb at 200 GeV (first error statistical, second systematic). From the pseudorapidity distribution of diffractive states we deduce the average number of charged particles to be 6.51.0 at 900 GeV and 4.11.1 at 200 GeV. Furthermore we report on our estimates for the cross-section of double-diffractive particle production at both Collider energies.
Zeitschrift für Physik C 05/1986; 33(2):175-185.
-
G. J. Alner,
R. E. Ansorge,
B. Åsman,
C. N. Booth,
L. Burow,
P. Carlson,
C. DeClercq,
R. S. DeWolf,
A. Drees,
B. Eckart, [......],
H. Schmickler,
F. Triantis,
L. Van hamme,
Ch. Walck,
C. P. Ward,
D. R. Ward,
C. J. S. Webber,
T. O. White,
G. Wilquet,
N. Yamdagni
[show abstract]
[hide abstract]
ABSTRACT: Data on antiproton-proton cross sections at the c.m. energies 200 and 900 GeV are presented. The data were obtained at the CERN antiproton-proton Collider operated in a new pulsed mode in which the same beams were accelerated and decelerated between beam energies of 450 and 100 GeV. The properties of the machine determine the ratio of the luminosities at the two energies to about 1% and thus an accurate measurement of the ratioR of the inelastic cross sections could be made. We findR (=
900/
200)=1.200.010.02, where the first error is statistical and the second systematic. Interpolating existing data to estimate
ine1(200 GeV) this measurement ofR leads to
ine1(900 GeV)=50.3+0.4+1.0 mb. Using an extrapolated value of
e1/
tot we estimate the total cross section at 900 GeV to be 65.30.71.5 mb. Both the inelastic and total cross sections are compatible with a ln2
s dependence. Comparisons are made with different fits to the total cross section energy dependence.
Zeitschrift für Physik C 01/1986; 32(2):153-161.
-
C. N. Booth,
R. E. Ansorge,
J. R. Carter,
W. W. Neale, J. G. Rushbrooke,
A. J. Simmons,
D. R. Ward,
T. O. White,
R. A. Lewis, B. Y. Oh, M. Pratap
[show abstract]
[hide abstract]
ABSTRACT: We report on an experiment in which the SLAC 40-in. hybrid facility was exposed to an 8.8-GeV/c antiproton beam. Using external detectors we have identified a large fraction of nonannihilation events and thus obtained a clean sample of annihilation data. Using proton interactions taken in the same detector at the same energy we have made a detailed study of (p̅ p-pp) differences and explored their relationship to p̅ p annihilations.
Phys. Rev. D. 04/1983; 27(9).
-
D. Brick,
H. Rudnicka,
A. M. Shapiro,
M. Widgoff,
R. E. Ansorge,
J. R. Carter,
W. W. Neale, J. G. Rushbrooke,
D. R. Ward,
B. M. Whyman, [......],
T. Handler,
E. L. Hart,
Y. Eisenberg,
U. Karshon,
E. E. Ronat,
A. Shapira,
R. Yaari,
G. Yekutieli,
D. A. Ljung,
T. W. Ludlam
[show abstract]
[hide abstract]
ABSTRACT: We have studied the inclusive production of K*±(890) and Y*±(1385) in pp, π+p, and K+p interactions at 147 GeV/c. The experiment used the Fermilab 30-inch hydrogen bubble chamber with the hybrid spectrometer system. Results are based on a sample of 1916 observed KS and 932 observed A. Inclusive cross sections are given for K*± and Y*± production from the three beams, and comparisons are made with experiments at other energies. Feynman-x and transverse-momentum-squared distributions are also calculated. The results suggest that the K*- is entirely produced in the central region, while the K*+ includes a component from beam fragmentation. Comparisons are made with the additive quark model.
Phys. Rev. D. 04/1982; 25(9).
-
K. Alpgård,
R. E. Ansorge,
B. Åsman,
S. Berglund,
K. Berkelman,
D. Bertrand,
K. Böckmann,
C. N. Booth,
C. Buffam,
L. Burow, [......],
T. Saarikko,
F. Triantis,
Ch. Walck,
C.-P. Ward,
D. R. Ward,
G. Weber,
A. R. Weidberg,
T. O. White,
G. Wilquet,
N. Yamdagni
[show abstract]
[hide abstract]
ABSTRACT: First results from the UA5 detector on charged particle production at
√s = 540 GeV in the pseudorapidity range |ν| < 5 are
presented. The central region pseudorapidity density is 3.0 +/- 0.1 for
non-diffractive events. The central width of the observed
ν-distribution is narrower than expected from a simple extrapolation
of ISR data,suggesting an increase in the mean pt for hadron
production.
Physics Letters B 11/1981; 107:310-314. · 3.95 Impact Factor
-
D. Brick,
A. M. Shapiro,
M. Widgoff,
R. E. Ansorge,
J. R. Carter,
W. W. Neale, J. G. Rushbrooke,
D. R. Ward,
B. M. Whyman,
R. A. Burnstein, [......],
T. Handler,
E. L. Hart,
Y. Eisenberg,
U. Karshon,
E. E. Ronat,
A. Shapira,
R. Yaari,
G. Yekutieli,
D. A. Ljung,
T. W. Ludlam
[show abstract]
[hide abstract]
ABSTRACT: We have studied inclusive Δ++ production at 147 GeV/c in pp, K+p, π+p, and π-p interactions. All four reactions were detected with the same apparatus and analyzed in the same way. The energy dependence of the Δ++ cross section was found to be Ap-1+B for pp, K+p, and π+p interactions and constant for π-p interactions. The shape of the inclusive Δ++ distributions does not depend on the beam, while the magnitudes are proportional to the total cross sections. We have obtained the effective trajectory at the p-Δ++ vertex from a triple-Regge analysis and found that all results are consistent with predictions of a triple-Regge diagram where a Pomeron is exchanged at the beam vertex and a π at the target vertex.
Phys. Rev. D. 01/1980; 21(3).
-
M. Pratap,
R. Lewis,
B. Y. Oh,
G. A. Smith,
J. Whitmore,
R. E. Ansorge,
C. Booth,
P. Elcombe,
J. R. Carter,
W. W. Neale, J. G. Rushbrooke,
A. Simmons,
D. R. Ward,
T. O. White
[show abstract]
[hide abstract]
ABSTRACT: We have studied the inclusive reactions p̅ p→pπ±X at 8.9 GeV/c and compared them to the lepton-induced processes e-p→e-π±X and the photoproduction reactions γp→π±X. The naive quark-parton model is found to be quite successful in interpreting the results. The distribution of charge in the current-fragmentation region is consistent with production of π± via absorption of the current by fractionally charged valence antiquarks of the antiproton.
Phys. Rev. D. 03/1979; 19(7).
-
D. R. Ward,
R. E. Ansorge,
C. P. Bust,
J. R. Carter,
W. W. Neale, J. G. Rushbrooke,
B. Y. Oh,
M. Pratap,
G. A. Smith,
J. Whitmore,
C. T. Murphy,
R. Raja,
L. Voyvodic
[show abstract]
[hide abstract]
ABSTRACT: We present results on inclusive Δ++ (1236) production
in 100 GeV/c pp interactions. In the region t < 1 GeV2 we
find a cross section of 1.29 +/- 0.15 mb. Comparisons with pp
interactions at high energies show Δ++ production in pp
and pp interactions to be very similar. The decay angular distributions
of the Δ++ are consistent with production predominantly
through pion-exchange and the properties of the system recoiling from
the Δ++ are similar to those of real π+p
interactions. However, the pπ+ background is found to show
qualitatively similar behaviour. In contrast to the indications of
Δ++ production through pion exchange we also find
evidence that events proceeding through diffraction dissociation are
more likely to contain Δ++ than other events. We
present results on the forward production of Δ++ in
association with Δ++ and protons.
Work supported by the United States Department of Energy.
Nuclear Physics B 07/1978; 141:203-219. · 4.66 Impact Factor
-
R. Raja,
C. T. Murphy,
L. Voyvodic,
R. E. Ansorge,
C. P. Bust,
J. R. Carter,
W. W. Neale, J. G. Rushbrooke,
D. R. Ward,
B. Y. Oh,
M. Pratap,
G. Sionakides,
G. A. Smith,
J. Whitmore
[show abstract]
[hide abstract]
ABSTRACT: Inclusive and semi-inclusive ρ0 production in 100-GeV/c p̅ p interactions has been studied as a function of c.m. rapidity and transverse momentum. Cross sections are compared with those for p̅ p interactions at other energies, as well as pp and π±p interactions, over the range ∼2<plab<200 GeV/c. A measurement of the f0 production cross section has been made. Calculations of the contribution from ρ0 decay to prompt lepton production are presented.
Phys. Rev. D. 10/1977; 16(9).
-
[show abstract]
[hide abstract]
ABSTRACT: Results of a survey of strange-particle production in np interactions in the momentum range 4-8 GeV/c are presented. As details of 3-body events have already been published, the results for the most part concern 4- and 5-body events with no missing neutrals. Cross sections for production of the most prominent resonances are given, and the properties of certain quasi-3-body channels discussed and compared with the corresponding states produced in pp interactions. It is found that the Σ-(1385) resonance is produced very strongly in unfitted topologies and certain statistical tensors for its production are shown to be in agreement with the predictions of the quark model.
Phys. Rev. D. 06/1974; 10(1).
-
[show abstract]
[hide abstract]
ABSTRACT: The Bethe-Heitler theory of pair production by photons and of bremsstrahlung by electrons is compared with observations of these processes in a liquid-hydrogen bubble chamber. Agreement between theory and experiment is found within the statistical limits of the experiment which are typically ∼ ½% of the total cross sections studied. The form of the experiment also allows limits to be set on the production of new particles of mass less than 100 MeV in high-energy hadronic collisions.
Phys. Rev. D. 12/1972; 7(1).
-
[show abstract]
[hide abstract]
ABSTRACT: Data on the reaction ppπ+π− in the momentum range 2–25 GeV/c are analysed for features indicating double pomeron exchange (DPE). The moments of the ππ angular distributions are examined in the quasi three-body frame of reference which is analogous to the s-channel helicity frame for quasi two-body processes. Inequality constraints on the moments are shown to suggest the presence of both S and P waves of the ππ system in the relevant pp(ππ) kinematic region, arguing against the dominance of DPE. The energy dependence of cross sections for selected events in different ranges of ππ mass is shown to be in accord with the predictions of a double Regge exchange model incorporating pomeron-reggeon exchange and not DPE. Both the cross sections and the ππ angular distributions are also examined in the light of a reggeized one-pion exchange model.
Nuclear Physics B.
-
A.K. Nandi,
R.E. Ansorge,
J.R. Carter,
W.W. Neale, J.G. Rushbrooke,
C.P. Ward,
D.R. Ward,
C. Moore,
R. Raja,
L. Voyvodic, [......],
M. Pratap,
G.A. Smith,
J. Whitmore,
D.G. Hill,
M. Kazuno,
G. McClellan,
H.L. Price,
B. Sechi-Zorn,
G.A. Snow,
F. Svrcek
[show abstract]
[hide abstract]
ABSTRACT: We discuss a number of features of π−p interactions at 100 GeV/c, and in particular we attempt to understand the differences between π−p and interactions using data from the same experiment. The optics considered include the rates of strange particle production, charge transfer distributions, the partition of energy among various particle species and inclusive meson production in beam and target fragmentation regions, with special reference to constituent models of hadrons.
Nuclear Physics B.
