Inclusive and semi-inclusive ρ 0 production are studied in 205 GeV/ c pp interactions. The number of ρ 0 per inelastic event is 0.33 ± 0.06, so that (13 ± 2)% of the π − are products of ϱ 0 decay. The ρ 0 are found to be produced mainly near y = 0 and tend to have larger average transverse momentum than do pions.
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The differential cross sections for neutron-proton elastic charge-exchange scattering have been measured with a two-arm technique for incident neutron momenta between 22 and 65 GeV/ c and for values of the momentum transfer squared between 0.002 and 0.8 (GeV/ c ) 2 . The sharp forward peak observed previously at lower energies is also present at momenta up to 65 GeV/ c ; however the s dependence of the cross section is slowing down.
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Correlations between pions produced in pp collisions at 69 GeV/c are observed both for π−π+ and π−π−. Short-range correlations in rapidity are present fory1⋍y2 in both cases; an enhancement is seen aroundy1=y2=±1. Correlations between transverse variables are linked to those in rapidity for π−π− combinations, whereas the effect is essentially kinematical for π+π−.
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New experimental results are presented on proton-proton elastic scattering at centre-of-mass energies s =23 GeV and s =62 GeV . The data are obtained using the Split Field Magnet detector at the CERN Intersecting Storage Rings. The absolute differential cross-sections show an energy-dependent behaviour. The position of the diffraction minimum changes from t =(−1.44±0.02)GeV 2 at 23 GeV to (−1.26±0.03)GeV 2 at 62 GeV. The cross-section at the second maximum is increasing with s . The connection of these observations with the hypothesis of “geometrical scaling” is discussed.
63 K EVENTS.
380 K EVENTS.
Results are presented on the topological cross sections obtained for antiproton-proton interactions from an exposure of the Fermilab 30-inch bubble chamber to a 100 GeV/ c negative beam enriched in p 's. The p p inelastic cross section is found to be σ inel = 34.6 ± 0.4 mb, and the average inelastic charged particle multiplicity to be 〈 n 〉 = 6.74 ± 0.05.
ERRORS ARE STATISTICAL ONLY EXCEPT FOR 2-PRONG CROSS-SECTIONS.
EXPONENTIAL FIT TO ELASTIC T DISTRIBUTION TO CORRECT FOR AN APPARENT LOSS OF EVENTS AT SMALL -T.
MOMENTS OF 100 GEV/C AP P MULTIPLICITY DISTRIBUTION.
Inclusive Δ++(1236) production in π+p and pp interactions is consistent with one-pion exchange. The average charged multiplicity recoiling from the Δ++ is studied as a function of missing mass, M2, for both interactions.
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Using new data from 100 GeV c π − interactions, we find the energy dependence of the invariant cross-section in the target fragmentation (central) region to be consistent with an A + Bs − 1 2 (C + Ds − 1 4 ) behavior. The leading particle peak near x = + 1 exhibits a width in x which becomes smaller with increasing energy and an integrated cross section which is approximately energy independent.
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In an experiment performed at the CERN Intersecting Storage Rings (ISR), 11 e + e − pairs of high invariant mass value (> 2.5 GeV/c 2 ) have been observed. Of these events, 9 can be interpreted as arising from the reaction p + p → J (3.1) + anything. the cross-section for this reaction is estimated and compared with the result obtained at lower centre-of-mass energies.
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We have measured the inclusive cross sections for γ, Ks0, Λ, and Λ¯ production in π+p and pp interactions at 100 GeV/c and compared various inclusive distributions of the produced γ and Ks0.
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We have measured total cross sections for neutrons on protons, deuteriom, beryllium, carbon, aluminium, iron, copper, cadmium, tungsten, lead, and uranium for momenta between 30 and 300 GeV/ c . The measurements were carried out in a small-angle neutral beam at Fermilab. Typical accuracy of the data is 0.5 to 1%. The cross sections are consistent with an A 0.77±0.01 dependence over the entire momentum range. The cross sections are compared with theoretical predictions. Agreement is found only if inelastic screening is included. Nuclear radii obtained from our data are in good agreement with previous determinations.
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We have studied inclusive Δ++(1236) production for |tpΔ|<1.0 (GeV/c)2 in a 50 000 picture exposure of the 30-inch hydrogen bubble chamber to a 205 GeV/c proton beam. The inclusive Δ++ cross section for one hemisphere in the center-of-mass system is (1.30±0.14) mb. The mean charged multiplicity of the system recoiling off the Δ++ is in agreement with that for laboratory π−p interactions at the same energy in the center-of-mass frame. The inclusive Δ++ production is compared to inclusive Λ0 and proton production in the same experiment. The connection between Δ++ production and diffraction is discussed. We find that not all Δ++ come from the decay of a diffractively-produced state. The PT2 distribution for the Δ++ has a slope of (10.5±0.9) (GeV/c)−2 for PT2≲0.2 (GeV/c)2. This slope, together with the decay angular distribution of the Δ++ at small momentum transfer, suggests a strong pion-exchange contribution to the inclusive process. We compare the data to the expectation of a triple-Regge model with ρ- and π-exchange contributions.
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A very narrow resonance with a mass of 3.1 GeV/c2 is observed in the reaction n+Be→μ++μ−+X. The total cross section for this process, as well as its P⊥2 and x distribution, are given.
The cross section per nucleon times the branching ratio.
We present data on inclusive and semi-inclusive ϱ 0 production in 147 GeV/ c π − p interactions. We find a total cross section of 7.3 ± 1.3 mb. Most of this cross section is found in the lower topology events (⩽ 10 prongs), and in the central and forward rapidity regions. The P T 2 dependence of ϱ 0 production, 〈: n > ϱ 0 per event, and the ϱ 0 / π + ratios are also discussed.
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We report on partial results of the analysis of a p̄p backward elastic scattering experiment, between 175 and 750 MeV/ c . Various evidences are given of the resonant nature of a backward peak at the S-meson mass. Analysis leads to J PC =4 ++ , firmly connected to other experimental data with I G =1 − . All results agree for an assignment to the A 2 trajectory.
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The neutron-proton elastic differential cross section has been measured for incident momenta between 10 and 70 GeV/c and for values of the momentum transfer squared between 0.1 and 2.8 (GeV/c) 2 . The forward peak and the break at about ∣ t ∣ = 1 (GeV/ c ) 2 are very similar to corresponding pp data.
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The single diffraction dissociation process pp → (p π + π − )p has been studied at the CERN ISR at √ s = 45 GeV and 0.1 < − t < 0.6 GeV 2 . The reaction is dominated by nucleon resonance production: pp → pN (1520) and pp → pN(1688) with cross-sections (0.25 ± 0.08) mb and (0.56 ± 0.19) mb respectively.
DIFFERENTIAL CROSS SECTIONS FOR THREE RANGES OF <P PI+ PI-> MASS.
FROM BREIT-WIGNER PLUS BACKGROUND FITS. CORRECTIONS FOR OTHER DECAY MODES USE THE PDG 1974 TABLES FOR N(1520) AND N(1688).
In a 35 000-picture exposure of the Fermilab 30-in. hydrogen bubble chamber to a 300-GeV/c proton beam 1863 neutral V0's were measured. The inclusive cross sections for γ, Ks0, Λ0Σ0, and Λ¯0Σ¯0 are 257 ± 18 mb, 7.3 ± 0.6 mb, 3.6 ± 0.4 mb, and 1.0 ± 0.3 mb, respectively. The correlation with charged particles and other inclusive features are studied.
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In an exposure of the Fermi National Accelerator Laboratory 30-in. bubble chamber to a beam of 205-GeV/c protons, we have determined total and differential cross sections for the inclusive reactions p+p→γ+X, π0+X, (K0K¯0)+X, Λ+X. Invariant distributions in x indicate that for γ, K0, Λ production, scaling has set in somewhere before 69 GeV. The γ differential cross sections are consistent with the relation dσdPu(π0)=12[dσdPu(π+)+dσdPu(π−)] for all Pu, where Pu=PL* or P⊥. The differential cross sections for Λ and K0 production indicate a break in the distribution at |t−tmin|=1.5(GeVc)2 and 0.5(GeVc)2, respectively. The Λ polarization is found to be - (0.25 ± 0.26), consistent with zero throughout the x region.
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Inclusive proton production in pp interactions at 205 GeV/c is studied using the Fermi National Accelerator Laboratory (Fermilab) 30-in. bubble chamber. The invariant cross section is presented in terms of several kinematic variables and compared with similar data obtained from counter experiments at Fermilab and at the CERN Intersecting Storage Rings (ISR). An important feature of this experiment is that it provides data for much wider ranges of the four-momentum transfer than have been attained in the counter experiments. It also gives full information on the associated charged-particle multiplicity of every event, thus permitting a detailed investigation of how various kinematic quantities depend on this parameter.
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We present results of measurements of the n−p total cross section between 30 and 280 GeV/c. The measurements were carried out with a neutron beam by using the standard transmission technique and a liquid-hydrogen target. A total-absorption calorimeter was used to determine the neutron energy. Our measurements, which have an accuracy of ∼1%, indicate a smooth rise of approximately 1.5 mb between 50 and 280 GeV/c. The combined n−p and p−p data above 20 GeV/c are well fitted by the expression σ=38.4+0.85|ln(s95)|1.47 mb.
MOST DATA TAKEN WITH 300 GEV/C INCIDENT PROTONS TO PRODUCE THE NEUTRON BEAM, WITH SOME ALSO USING 200 GEV/C PROTONS.
In a 35 000-picture exposure of the 30-in. hydrogen bubble chamber to a 300-GeV/c proton beam at the Fermi National Accelerator Laboratory, 10054 interactions have been observed. The measured total cross section is $40.68 \pm 0.55$ mb, the elastic cross section is $7.89 \pm 0.52$ mb, and the average charged-particle multiplicity for inelastic events is $8.S0 \pm 0.12$.
QUOTED ERRORS INCLUDE EFFECTS OF CORRECTIONS.
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Data from p+p→p+X at 102, 205, and 405 GeV and from π−+p→p+X at 205 GeV exhibit an approximate scaling property in the charged-prong multiplicity distributions as a function of the missing mass for the range 5<~MX<~13 GeV.
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Inclusive spectra of π − production for pp interactions are discussed at 69 GeV/ c both in the central and in the fragmentation region and are compared to data at lower and higher energies. The p T dependence of the invariant structure function is also analysed.
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The charged-particle multiplicity distribution in 205−GeVc proton-proton interactions is presented. In addition, the total diffractive contributions to each charged multiplicity are estimated assuming a factorizable Pomeron.
THE TOTAL CROSS SECTION NORMALIZATION COMES FROM THIS AND OTHER EXPERIMENTS.
We have measured total cross sections for p−p scattering with the results σT=40.42±0.27 mb at 200 GeV/c and 40.40 ± 0.28 mb at 300 GeV/c. Our 300-GeV/c result is significantly higher than published data from the CERN intersecting storage rings. Our data, taken together with the Serpukhov data, indicate that the cross section rises ≅ 2 mb between 60 and 250 GeV. The variation of the cross section with energy may be more complicated than the a+blnsα behavior commonly assumed for Elab≳50 GeV.
Axis error includes +- 0.0/0.0 contribution (QUOTED ERRORS ARE COMBINED STATISTICAL AND SYSTEMATIC).
We present an analysis, in the framework of the triple Regge model, of our recent experimental results on the reaction p+p→p+X between 50 and 400 GeV.
The cross sections is fitted in the framework of the triple Regge model. The symbols P and R in the (C=...) denote pomeron and reggeon, respectively. For fit I and II the authors used conventional trajectories alpha(P) = 1 +0.25*T, alpha(R) = 0.5 + T. Fit II is restricted to data with (1 - M(P=4)**2/S) > 0.84. In fit III they use alpha(R) = 0.2 + T for the RRP term. Fit IV is like fit I with additional fixed (pion pion P) term.
The cross sections is fitted in the farmework of the triple Regge model. The symbols P and R in teh (C=...) denote pomeron and reggeon, respectively. CONST(C=C) and SLOPE are from the replacement of the RRP term by the exponential one : CONST(C=C)*(SLOPE*(1-x)). See text for detail.
We present measurements of the invariant cross section for the inclusive reaction p+p→p+X in the region 0.14<|t|<0.38 GeV2, 100<s<750 GeV2, and 0.80<x<0.93.
The cross sections are fitted by the formula CONST(C=A)*EXP(SLOPE*T)*(1+CO NST(C=B)/SQRT(S)).
From analysis of V0 events observed in an exposure of the National Accelerator Laboratory 30-in. bubble chamber to 303−GeVc protons, we obtain these results: (1) 〈nπ0〉 rises approximately linearly with n-, implying strong coupling of neutral and charged pions, while 〈nKS0〉 is less coupled to n; (2) γ, KS0, and Λ0 production cross sections are approaching a scaling limit by 303 GeVc; (3) within the limited statistics, dσdy is flat in the central region for KS0 and low-multiplicity γ events.
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Invariant cross-sections are presented for the inclusive reaction p + p → π o + anything, Measurements of large transverse momentum π o 's (2.5 GeV/ c < p ⊥ <9 GeV/ c ) were made near 90° at the CERN ISR at five centre-of-mass energies (√ s = 23.5, 30.6, 44.8, 52.7 and 62.4 GeV. At large p ⊥ , the invariant cross-sections are seem to vary with s and p ⊥ , in good agreement with a fit of the form Ap ⊥ − n F ( p ⊥ /√ s ), with n ≈8 and F ( p ⊥ /√ s )≈ exp (−26 p ⊥ /√ s ).
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Inclusive π− distributions from 205-GeV/c pp interactions, covering the full range of longitudinal and transverse momenta, have been obtained using the 30-in. hydrogen bubble chamber at the National Accelerator Laboratory. These data provide new evidence for scaling in the fragmentation region and for a plateau in the central region of rapidity. The 90°-c.m. invariant cross section varies as exp[−(10±2)PT2] in the range PT2<~0.1 (GeV/c)2.
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The inelastic reaction p+p→p+X is studied at 205 GeV/c. The distribution of the square of the missing mass, M2, shows a large diffractivelike peak at low M2 due to two-, four-, and six-prong events. The slope of the invariant cross section versus t decreases with increasing M2. The energy dependences of the multiplicity moments for the recoiling system X are similar to those for corresponding moments for p+p→(n chargedparticles).
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The transverse momentum distribution at 90° of pions, protons and antiprotons have been measured at the CERN intersecting storage rings for C.M. energies between 23.2 and 52.7 GeV. In this energy range, the pion and proton distributions are almost energy independent. The antiproton production rises by a factor of two between 23.2 and 52.7 GeV.
The invariant cross section was fitted by CONST*EXP(-SLOPE*PT).
The invariant cross section was fitted by CONST*EXP(-SLOPE(C=1)*PT+SLOPE(C=2)*PT**2).
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Proton-proton elastic scattering has been measured at the CERN Intersecting Storage Rings in the four-momentum transfer range 0.001 ⩽… t …⩽ 0.015 GeV 2 at centre-of-mass energies of 23 and 31 GeV. The detection of Coulomb scattering and of its interference with nuclear scattering leads to the determination of the real part of the nuclear amplitude and of the total proton-proton cross section by the optical theorem.
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In an exposure of the chamber Mirabelle at the Serpukhov accelerator, 1 943 interactions at 50 GeV/ c and 8 959 at 69 GeV/ c have been observed. Topological cross sections and charged multiplicity distributions are presented. The average charged multiplicities found are respectively 5.32 ± 0.13 and 5.89 ± 0.07.
2PRONG INELASTIC CROSS SECTIONS DERIVED BY SUBTRACTION OF OTHER PRONG CROSS SECTIONS AND KNOWN ELASTIC MEASUREMENTS FROM THE TOTAL.
In an exposure of the 30-in. hydrogen bubble chamber to a 303−GeVc proton beam, 2245 interactions have been observed. The measured total cross section is 39.0±1.0 mb and the average charged particle multiplicity 〈nch〉=8.86±0.16.
TOPOLOGICAL CROSS SECTIONS.
We have investigated the above processes at the CERN Intersecting Storage Rings (ISR). Results show a marked change of the slope parameter b ( t , s ) = (d/d t ) ln (d σ /d t ) around − t ≈ 0.10 GeV 2 . The s − and t − dependence of b ( t , s ) have been observed over the interval 460 GeV 2 < s < 2900 GeV 2 and 0.02 GeV 2 < t < 0.40 GeV 2 .
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The single-particle inclusive pion spectrum from the reaction p + p → π ± + anything at 28.5 GeV is presented in both tabular and graphical form. The data are from exposures in the BNL 203 cm bubble chamber. The emphasis of this paper is on exhibiting the single-particle spectra in sufficient detail so that the data will be useful to those interested in testing models and developing new concepts.
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This work extends our previous investigations at the CERN Intersecting Storage Rings, with improved statistics at three different energies, wider angular range and a better control over systematic errors. Values for the (diffraction) shape parameter b are given.
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Proton-proton elastic scattering has been measured over the angular range 7 to 16 mrad at centre-of-mass energies of 31, 45 and 53 GeV using the CERN Intersecting Storage Rings. The results indicate that the diffraction peak has continued to shrink with increasing energy, but not as fast as suggested by the results at lower energies.
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Small angle elastic scattering events have been observed at the CERN Intersecting Storage Rings. Directions of both particles as well as the collision vertex are reconstructed with the help of four sets of spark chambers, two for each of the two arms. The elastic nature of the events is demonstrated by a collinearity requirement. We find values for the (diffraction) slope parameter in disagreement with the simple linear extrapolation of lower energy (Surpukov) data.
NUMBER OF EVENTS 87364.
NUMBER OF EVENTS 8305.
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