-
Ames-Bologna-CERN-Dortmund-Heidelburg-Warsaw Collaboration (A. Breakstone,
R. Campanini,
H. B. Crawley,
M. Cuffiani,
G. M. Dallavalle,
M. M. Deninno,
K. Doroba, D. Drijard,
F. Fabbri,
A. Firestone, [......],
B. Rensch,
F. Rimondi,
M. Schmelling,
G. P. Siroli,
R. Sosnowski,
M. Szczekowski,
O. Ullaland,
D. Wegener,
M. Wunsch,
R. Yeung
[show abstract]
[hide abstract]
ABSTRACT: In a high-statistics experiment at the CERN-ISR we analyze the variation of the average transverse momentum in fixed rapidity intervals as a function of the multiplicity density of charged particles produced in proton-proton collisions at √s = 31, 44 and 62 GeV. The average transverse momentum depends on both rapidity y and charged multiplicity density, ρ = Δn/Δy. The dependence on ρ changes gradually from an increase at low y, constancy at intermediate y and decrease at large y.
EPL (Europhysics Letters) 07/2007; 7(2):131. · 2.17 Impact Factor
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B Adeva,
L Afanasyev,
M Benayoun,
A Benelli,
Z Berka,
V Brekhovskikh,
G Caragheorgheopol,
T Cechak,
M Chiba,
S Constantinescu, [......],
M J Tobar,
S Trusov,
V Utkin,
O Vázquez Doce,
P Vázquez,
S Vlachos,
V Yazkov,
Y Yoshimura,
M Zhabitsky,
P Zrelov
[show abstract]
[hide abstract]
ABSTRACT: The goal of the DIRAC experiment at CERN is to measure with high precision the lifetime of the π+π− atom (A2π), which is of order 3 × 10−15 s, and thus to determine the s-wave ππ-scattering lengths difference |a0 − a2|. A2π atoms are detected through the characteristic features of π+π− pairs from the atom break-up (ionization) in the target. We report on a first high statistics atomic data sample obtained from p–Ni interactions at 24 GeV/c proton momentum and present the methods to separate the signal from the background.
Journal of Physics G Nuclear and Particle Physics 11/2004; 30(12):1929. · 4.18 Impact Factor
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Ames-Bologna-CERN-Dortmund-Heidelberg-Warsaw Collaboration,
A. Breakstone,
H. B. Crawley,
A. Firestone,
M. Gorbics,
L. D. Isenhower,
J. W. Lamsa,
W. T. Meyer,
R. Campanini,
M. Cuffiani, [......],
M. Heiden,
W. Herr,
E. E. Kluge,
T. Nakada,
A. Putzer,
B. Rensch,
K. Doroba,
R. Gokieli,
R. Sosnowski,
M. Szczekowski
[show abstract]
[hide abstract]
ABSTRACT: Measurements are presented of inclusive charged particle production in proton-proton collisions at √s=31, 44 and 62 GeV at the CERN ISR. The large acceptance of the Split Field Magnet detector allows a single experimental setup
to cover almost the full longitudinal phase space up to a transverse momentum of 3 GeV/c.
Zeitschrift für Physik C 11/1995; 69(1):55-65.
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JETSET Collaboration,
L. Bertolotto,
A. Buzzo,
P. T. Debevec, D. Drijard,
S. Easo,
R. A. Eisenstein,
W. Eyrich,
M. Ferro-Luzzi,
J. Franz, [......],
M. Rook,
E. Rössle,
A. Santroni,
H. Schmitt,
O. Steinkamp,
F. Stinzing,
B. Stugu,
M. Tscheulin,
H. Wirth,
H. Zipse
[show abstract]
[hide abstract]
ABSTRACT: The reaction
[`(p)]p ® ff\bar pp \to \phi \phi
is investigated in the JETSET (PS202) experiment using an internal target in LEAR. Data have been analysed at a variety of
beam momenta from 1.2 GeV/c to 2.0 GeV/c, corresponding to centre-of-mass energies between 2.15 GeV and 2.43 GeV. A strong
φφ-signal was observed over the whole, energy range, preliminary results giving φφ-yields of (1–2) μb. No evidence for narrow
resonances was found within the accumulated statistics. The capability of the experiment to measure φ→K+K− decay angular distributions and thus put constraints on the spin-parity quantum numbers of a possible resonant intermediate
state is demonstrated.
Il Nuovo Cimento A 10/1994; 107(11):2329-2337.
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A. Breakstone,
R. Campanini,
H. B. Crawley,
G. M. Dallavalle,
M. M. Deninno,
K. Doroba, D. Drijard,
F. Fabbri,
A. Firestone,
H. G. Fischer, [......],
B. Rensch,
F. Rimondi,
M. Schmelling,
G. P. Siroli,
J. D. Skeens,
R. Sosnowski,
M. Szczekowski,
O. Ullaland,
D. Wegener,
R. Yeung
[show abstract]
[hide abstract]
ABSTRACT: Data are presented on pomeron-pomeron interactions which produce a central +–+– system in proton-proton collisions at s=62 GeV at the CERN Intersecting Storage Rings. A spin-parity analysis of the +–+– system shows evidence for the production of the statef
2 (1720) with decay to 0+–. Since pomeron-pomeron interactions are expected to favor the production of gluonic bound states, observation of thef
2 (1720) supports earlier interpretations of it as a glueball. In addition, enhancements near threshold give indication of the statef
2 (1270) decaying to 00 and the statef
0 (1400) decaying to 0+–.
Zeitschrift für Physik C 05/1993; 58(2):251-256.
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A. Breakstone,
C. D. Buchanan,
R. Campanini,
H. B. Crawley,
M. Cuffiani,
G. M. Dallavalle,
M. M. Deninno,
K. Doroba, D. Drijard,
F. Fabbri, [......],
B. Rensch,
F. Rimondi,
M. Schmelling,
G. P. Siroli,
J. Skeens,
R. Sosnowski,
M. Szczekowski,
O. Ullaland,
D. Wegener,
R. Yeung
[show abstract]
[hide abstract]
ABSTRACT: A comparison of QCD parton models with events including a high transverse momentum trigger particle is performed. The data were obtained with the Split Field Magnet (SFM) detector at the CERN ISR. The effective intrinsic transverse momentum, k
T
, of a parton is found to be about 1 GeV/c from an analysis of inclusive cross sections based upon lowest order parton-parton scattering. Large values of k
T
are also needed to obtain a good description of the particle density in the azimuthal hemisphere opposite to the trigger. The measured recoil of the spectator jets tends to require much smaller values of k
T
. The model is improved by including higher-order QCD effects. Thus, starting from k
T
=0.45 GeV/c, an effective k
T
of about 1 GeV/c at hard scattering is generated through perturbative parton showers, which provides a consistent description of the measurements in full phase space. This analysis shows therefore that well-known problems of lowest-order QCD calculations can be resolved by inclusion of higher-order effects.
Zeitschrift für Physik C 11/1991; 52(4):551-557.
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C Albajar,
M G Albrow,
O C Allkofer,
K Ankoviak,
R Apsimon,
B Aubert,
C Bacci,
S Bartha,
G Bauer,
A Bettini, [......],
M Mohammadi,
K Morgan,
A Morsch,
A Moulin,
T Muller,
R Munoz,
L Naumann,
P Nedelec,
M Nikitas,
others
[show abstract]
[hide abstract]
ABSTRACT: An analysis of W and Z boson production at UA1, using 4.66 pb-1 of data from the 1988 and 1989 CERN ppBAR Collider runs at square root of s = 0.63 TeV, yields R = sigma(w)Br(W --> mu-v)/sigma(z)Br(z --> mu-mu) = 10.4(-1.5)(+1.8)(stat.) +/- 0.8(syst). We find R = 9.5(-1.0)(+1.1)(stat. + syst.) when combining all available UA1 data, in both the electron and muon channel, taken in the period 1983-1989. In the framework of the standard model, the value of R is used to infer the total width of the W boson, I(w) (tot) = 2.18(-0.24)(+0.26) (exp.) +/- 0.04 (theory) GeV/c2.
Physics Letters B. 01/1991; 253(3-4).
-
C Albajar,
M G Albrow,
O C Allkofer,
K Ankoviak,
R Apsimon,
B Aubert,
C Bacci,
S Bartha,
G Bauer,
A Bettini, [......],
T Moers,
M Mohammadi,
K Morgan,
A Morsch,
A Moulin,
T Muller,
R Munoz,
L Naumann,
P Nedelec,
others
[show abstract]
[hide abstract]
ABSTRACT: We report on a new measurement of B0-BBAR0 mixing at the CERN SppBARS Collider. Mixing is measured in the non-isolated high mass dimuon sample using data from the 1988-1989 collider runs. The measured value of the mixing parameter, chi, is 0.145 +/- 0.035(stat.) +/- 0.014(syst.). The average of this measurement and that from our 1984-1985 data is chi = 0.148 +/- 0.029(stat.) +/- 0.017(syst.) assuming fully correlated systematic errors. Using the measurement of chi-d from ARGUS and CLEO, we obtain chi-s = 0.50 +/- 0.20, which gives a limit of chi-s > 0.17 (0.12) at 90% (95%) CL. Including the measurements of chi from the ALEPH and L3 experiments gives chi-s = 0.53 +/- 0.15, and a limit of chi-s > 0.27 (0.23) at 90% (95%) CL.
Physics Letters B. 01/1991; 262(1).
-
C Albajar,
M G Albrow,
O C Allkofer,
K Ankoviak,
R Apsimon,
B Aubert,
C Bacci,
S Bartha,
G Bauer,
A Bettini, [......],
T Moers,
M Mohammadi,
K Morgan,
A Morsch,
A Moulin,
T Muller,
R Munoz,
L Naumann,
P Nedelec,
others
[show abstract]
[hide abstract]
ABSTRACT: We report on a search for the decays B0 --> mu+mu-, B --> mu+mu-X and B(d)0 --> mu+mu-K0*, which are expected to be rare if mediated by flavor changing neutral currents. Using data collected during the 1984-1989 CERN ppBAR Collider runs, the UA1 search was carried out using mu+mu- events with 3.9 < M(mu-mu) < 5.5 GeV/c2. We find 90% confidence level upper limits on the branching ratios for B0 --> mu+mu- of 8.3 x 10(-6), for B --> mu+mu-X of 5.0 x 10(-5), and for B(d)0 --> mu+mu-K0* of 2.3 x 10(-5). Implications for upper limits on the t-quark mass are discussed.
Physics Letters B. 01/1991; 262(1).
-
C Albajar,
M G Albrow,
O C Allkofer,
K Ankoviak,
R Apsimon,
B Aubert,
C Bacci,
S Bartha,
G Bauer,
A Bettini, [......],
T Moers,
M Mohammadi,
K Morgan,
A Morsch,
A Moulin,
T Muller,
R Munoz,
L Naumann,
P Nedelec,
others
[show abstract]
[hide abstract]
ABSTRACT: We have measured the production cross-section times branching ratio for J/PSI --> mu+ mu- in ppBAR interactions at square-root s = 630 GeV in the kinematic range /y/ < 2.0 and p(T) > 5 GeV/c, BR (J/PSI --> mu+ mu-)sigma(ppBAR --> J/PSI) = 6.18 +/- 0.24 +/- 0.81 nb. The data sample collected in 1988 and 1989 for an integrated luminosity of 4.7 pb-1 represents a fivefold improvement over the statistics in our earlier study of the J/PSI production process, and the P(T) distribution which is measured extends to 28 GeV/c. Using event topology we show that the rate for the direct production of J/PSI, via radiative decays of chi-states, is larger than that for production via B-hadrons. Production of PSI' is also studied using the decay modes PSI' --> mu+ mu- and PSI' --> J/PSI-pi+pi-.
Physics Letters B. 01/1991; 256(1):112-120.
-
C Albajar,
M G Albrow,
O C Allkofer,
K Ankoviak,
R Apsimon,
B Aubert,
C Bacci,
S Bartha,
G Bauer,
A Bettini, [......],
T Moers,
M Mohammadi,
K Morgan,
A Morsch,
A Moulin,
T Muller,
R Munoz,
L Naumann,
P Nedelec,
others
[show abstract]
[hide abstract]
ABSTRACT: We report measurements of b-quark and B-hadron production in ppBAR collisions at square-root s = 630 GeV. We use muon data samples to extract beauty production cross-sections over a wide range of transverse momentum in the central rapidity range /y/ < 1.5. We compare our results to an O(alpha-s3) QCD prediction and find good agreement over the measured b-quark transverse momentum range 6 GeV/c to 54 GeV/c. Using the shape of the P(T) and y distributions predicted by QCD to extrapolate our data, we infer a total cross-section for b-quark production at square-root s = 630 GeV of sigma(ppBAR --> bbBAR + X) = 19.3 +/- 7 (exp.) +/- 9 (th.)mu-b.
Physics Letters B. 01/1991; 256(1):121-128.
-
A. Breakstone,
R. Campanini,
H. B. Crawley,
G. M. Dallavalle,
M. M. Deninno,
K. Doroba, D. Drijard,
F. Fabbri,
A. Firestone,
H. G. Fischer, [......],
B. Rensch,
F. Rimondi,
M. Schmelling,
G. P. Siroli,
J. D. Skeens,
R. Sosnowski,
M. Szczekowski,
O. Ullaland,
D. Wegener,
R. Yeung
[show abstract]
[hide abstract]
ABSTRACT: Data are presented on Pomeron-Pomeron interactions which produce a centralÖs = 62 GeV\sqrt s = 62 GeV
at the CERN Intersecting Storage Rings. This process may favor the production of gluonic bound states. A partial-wave analysis of the
+
– system shows evidence for the production of the statesf
0(975),f
0(1400), andf
2(1270). The fitted mass for thef
2(1270) is about 50 MeV below the world average. In addition, the production mechanism for thef
2(1270) is uniquely different from that for the other final states in that there is a correlation between the outgoing protons. this is consistent with a picture of two-gluon exchange with thef
2(1270) produced by gluon fusion, and could indicate that thef
2(1270) has a glueball component.
Zeitschrift für Physik C 11/1990; 48(4):569-575.
-
[show abstract]
[hide abstract]
ABSTRACT: Data on the free ion yield produced by γ-radiolysis of
neopentane (NP), 2,2,4,4-tetramethylpentane (TMP), tetramethylsilane
(TMS), tetramethylgermanium (TMG), and tetramethyltin (TMSn) are
analyzed using Onsager theory. Four distributed functions describing the
separation distance between electron-ion pairs at thermalization were
considered: a delta function (DELTA), an exponential function (EXP), an
exponential modified by a first power of r (R1EXP), and an
exponential modified by a quadratic power of r (R2EXP). With a
suitable choice of adjustable parameters, G (∞) and ρ,
where G (∞) is the number of electron-ion pairs initially
produced per every 100 eV released in the sample and ρ is the mean
thermalization distance, all four distributions approximately describe
the data. For NP, TMP, and TMG, the data are best described by R1EXP;
for TMSn, R2EXP is best
Conduction and Breakdown in Dielectric Liquids, 1990. ICDL 1990. Conference Record., 10th International Conference on; 10/1990
-
C. Albajar,
M. G. Albrow,
O. C. Allkofer,
B. Andrieu,
K. Ankoviak,
R. Apsimon,
B. Aubert,
C. Bacci,
S. Bartha,
G. Bauer, [......],
V. Vuillemin,
K. Wacker,
G. Walzel,
X. Wu,
C. -E. Wulz,
M. Yvert,
I. Zacharov,
L. Zanello,
Y. Zolnierowski,
P. Zotto
[show abstract]
[hide abstract]
ABSTRACT: We report on a search for new heavy quarks decaying semileptonically into muons, using 4.7 pb–1 of data taken during the CERN
p[`(p)]p\bar p
collider runs in 1988 and 1989. The properties of isolated muons accompanied by jets are consistent with the predictions from the Standard Model but do not show a signal for a new heavy quark. Combining all the UA1 data (5.4 pb–1), lower mass limits are obtained at 60 GeV/c2 (95% CL) for thet-quark and 43 GeV/c2 (95% CL) for a fourth-generation charge-1/3 quark (b-quark).
Zeitschrift für Physik C 02/1990; 48(1):1-12.
-
C Albajar,
M G Albrow,
O C Allkofer,
B Andrieu,
K Ankoviak,
R Apsimon,
B Aubert,
C Bacci,
S Bartha,
G Bauer, [......],
M Markytan,
M A Marquina,
R Martinelli,
G Maurin,
S McMahon,
J P Mendiburu,
A Meneguzzo,
J P Merlo,
T Meyer,
others
Zeitschrift Fur Physik C-Particles and Fields. 01/1990; 48(1):1-12.
-
C Albajar,
M G Albrow,
O C Allkofer,
B Andrieu,
K Ankoviak,
R Apsimon,
B Aubert,
C Bacci,
S Bartha,
G Bauer, [......],
G Maurin,
S McMahon,
J P Mendiburu,
A Meneguzzo,
J P Merlo,
T Meyer,
T Moers,
M Mohammadi,
K Morgan,
others
Physics Letters B. 01/1990; 244(3-4):566-572.
-
C Albajar,
M G Albrow,
O C Allkofer,
K Ankoviak,
R Apsimon,
B Aubert,
C Bacci,
S Bartha,
G Bauer,
A Bettini, [......],
T Moers,
M Mohammadi,
M Morgan,
A Morsch,
B Mours,
A Moulin,
T Muller,
R Munoz,
L Naumann,
others
Nuclear Physics B. 01/1990; 345(1).
-
A. Breakstone,
R. Campanini,
H. B. Crawley,
M. Cuffiani,
G. M. Dallavalle,
M. M. Deninno,
K. Doroba, D. Drijard,
F. Fabbri,
A. Firestone, [......],
K. Rauschnabel,
B. Rensch,
F. Rimondi,
M. Schmelling,
G. P. Siroli,
R. Sosnowski,
M. Szczekowski,
O. Ullaland,
D. Wegener,
R. Yeung
[show abstract]
[hide abstract]
ABSTRACT: The contribution of single diffraction dissociation to highp
T
particle production has been determined with the split field magnet detector. For transverse momentap
T
>2 GeV/c and production angles >10 it is found to be less than 5% for all types of trigger particles. Specifically, a diffractive origin of the large production cross section for highp
T
protons can be excluded. The contributions found to highp
T
production are found to be in good agreement with extrapolations of the relative particle yields from single diffraction dissociation observed in inelastic minimum bias events.
Zeitschrift für Physik C 05/1988; 40(2):207-214.
-
A. Breakstone,
R. Campanini,
H. B. Crawley,
M. Cuffiani,
G. M. Dallavalle,
M. M. Deninno,
K. Doroba, D. Drijard,
F. Fabbri,
A. Firestone, [......],
K. Rauschnabel,
B. Rensch,
F. Rimondi,
M. Schmelling,
G. P. Siroli,
R. Sosnowski,
M. Szczekowski,
O. Ullaland,
D. Wegener,
R. Yeung
[show abstract]
[hide abstract]
ABSTRACT: Proton-proton interactions which result in a central cluster of massM
x
and two quasi-elastically scattered protons are generally described by Pomeron-Pomeron scattering. A study of this process at ISR energies with the Split Field Magnet detector is carried out in terms of transverse momentum behaviour for the centrally produced system of particles. The inclusivep
T
distribution for central hadrons is measured up to 3 GeV/c. Forp
T
p
T
distribution is exponential. Using a subsample of exclusive events, this exponential shape is shown to originate from a phase-space-like decay ofM
x
when convoluted with a transverse component of the pomeron momentum. In the highp
T
range, the shape of thep
T
distribution strongly depends on Feynman-x of the scattered protons in a way that can be described by hard parton scattering.
Zeitschrift für Physik C 02/1988; 40(1):41-47.
-
A. Breakstone,
R. Campanini,
H. B. Crawley,
M. Cuffiani,
G. M. Dallavalle,
M. M. Deninno,
K. Doroba, D. Drijard,
F. Fabbri,
A. Firestone, [......],
B. Rensch,
F. Rimondi,
M. Schmelling,
G. P. Siroli,
R. Sosnowski,
C. Stubenrauch,
M. Szczekowski,
O. Ullaland,
D. Wegener,
R. Yeung
[show abstract]
[hide abstract]
ABSTRACT: Events are analyzed in which a high transverse momentum proton was produced at polar angles of 10, 20 and 45. The experiment was performed with the Split Field Magnet detector at the CERN ISR at
Ös\sqrt s
=62 GeV. A 4-jet structure of these events is found [1]. The measured charge structure of spectator jets is compatible with proton production from hard diquark scattering. This is supported by a study of baryon number compensation in the towards jets. The observed charge compensation in the towards jets suggests dominance of hard (ud) scattering. Evidence for
++
production at high transverse momentum indicates the presence of an additional (uu) scattering component. The properties of the recoiling away jets are compatible with the fragmentation of a valence quark and/or of a gluon as in the case of meson triggers.
Zeitschrift für Physik C 11/1987; 36(4):567-576.
