H. Jöstlein

Precision measurement of proton-proton total cross section at the CERN intersecting storage rings

Abstract The measurement of the proton-proton total cross section performed by the CERN-Pisa-Rome-Stony Brook Collaboration at the CERN ISR is discussed in detail. The total interaction rate, the elastic scattering rate in the forward direction, and the machine luminosity were measured simultaneously to obtain three different determinations of the total cross section. Consistent results were found, which made it possible to prove the reliability of the Van der Meer luminosity calibration within +-0.9% and to achieve a precision of +-0.6% in the measurement of the total cross section.

New measurements of proton-proton total cross section at the CERN intersecting storage rings

Abstract Measurements of the proton-proton total cross section have been made with increased precision (±0.6%) over the ISR energy range s =23.5−62.7 GeV . Two different experimental methods gave consistent results, showing that the total cross section increases 10% over the ISR range and in addition that the absolute value of the ISR luminosity can be measured to ±0.9%.

Measurement of charged particle multiplicities associated with large transverse momentum photons in proton-proton collisions

Abstract We have measured the behaviour or charged-particle multiplicities as a function of the transverse momentum of photons produced at 90° in proton-proton collisions. The data were obtained at the CERN Intersecting Storage Rings (ISR) at a centre-of-mass energy of 53 GeV and cover the transverse momentum range 0

Measurement of Two-Particle Semi-Inclusive Rapidity Distributions at the CERN ISR.

SummaryWe present data on the semi-inclusive distributions of rapidities of secondary particles produced in pp collisions at very high energies. Our experiment was performed at the CERN Intersecting Storage Rings (ISR). The data given here, at centre-of-mass energies of √s=23 and 62 GeV, include the single-particle distributions and two-particle correlations. The semi-inclusive correlations show pronounced short-range correlation effects which have a width considerably narrower than in the case of inclusive correlations. We show that these short-range effects can be understood empirically in terms of three parameters whose energy and multiplicity dependence are studied. The data support the picture of multiparticle production in which clusters of small multiplicity and small dispersion are emitted with subsequent decay into hadrons.RiassuntoVengono presentati dati sulle distribuzioni inclusive in rapidità dei secondari carichi prodotti nelle collisioni protone-protone ad altissime energie. L’esperimento è stato eseguito agli Anelli ad Intersezione (ISR) del CERN. I dati, ad una energia √s=23 e 62 GeV nel centro di massa, comprendono le distribuzioni di particella singola e le correlazioni a due particelle per fissa molteplicità carica, come anche le correlazioni inclusive a due particelle. Le correlazioni semi inclusive mostrano forti effetti di correlazione a breve distanza, che hanno una larghezza molto più piccola che nel caso delle correlazioni inclusive. Nel lavoro si fa vedere che questi effetti a breve distanza possono essere capiti empiricamente in funzione di tre parametri di cui si studia la dipendenza dall’energia e dalla molteplicità. I dati favoriscono la descrizione della produzione a molti corpi in cui vengono emessi agglomerati di piccola molteplicità e piccola dispersione, che successivamente decadono in adroni.РеэюмеВ работе приводятся данные для полуинклюэивных распределений вторичных частиц, рожденных в рр соударениях при очень высоких знергиях. Нащ зксперимент был проиэведен на встречных накопительных кольцах в ЦЕРНе. Полученные в работе данные при знергиях в системе центра масс √s=23 и 62 ГзВ включают одночастичные распределения и двухчастичные корреляции при фиксированной множественности эаряженных частиц п, а также инклюэивные двухчастичные корреляции. Полуинклюэивные корреляции обнаруживают явно выраженные зффекты короткодействуюших корреляций, которые обладают щириной эначительно меньщей, чем в случае инклюэивных корреляций. Мы покаэываем, что зти короткодействуюшие зффекты могут быть общяснены змпрически в терминах трех параметров. Обсуждается эависимость зтих параметров от знергии и множественности. Полученные данные подтверждают картину множественного рождения, в которой испускаются кластеры с малой множественностью и малой дисперсией с последуюшим распадом в адроны.

Associated multiplicities in proton-proton collisions with a charged hadron at X =0 at the CERN ISR

SummaryCharged-particle multiplicities and angular distributions associated with a π±, K±, p and

Correlations of secondaries in events with a forward negative hadron at the ISR

\bar p

\Upsilon

produced at 90°, have been measured at the CERN ISR. The triggering particle was identified by a magnetic spectrometer, within a range of transverse laboratory momentumpT which was different for different particles: 0.075<pT<3.0 GeV/c for pions, 0.075<pT<1.5 GeV/c for kaons, 0.075<pT<3.0 GeV/c for protons and antiprotons. Associated multiplicities have been obtained as a function ofpT at the different ISR beam energies. The distributions of the associated particles have been studied as functions of the azimuthal angleϕ and of the pseudorapidityη. In the high-pT region associated multiplicities increase for all particle types approximately linearly withpT. The momentum of a high-pT particle is seen to be balanced over a wide cone ofϕ andη in the opposite hemisphere. An increase in the multiplicities of secondaries in the same hemisphere near the triggering particle is also observed for the high-pT baryons. At lowpT there is an increase in associated multiplicity on the same side as the transverse momentum of the pion approaches zero.RiassuntoSi presentano le misure effettuate agli ISR del CERN delle molteplicità e distribuzioni angolari delle particelle associate a π±, K±, p e