Sharmila Sarkar

Evidence of different pion coherence zones for 'hot' and 'cold' events in relativistic heavy-ion interaction

A comparison of the transverse momentum (PT) distribution of the alpha particles emitted as projectile fragments from the 12C-emulsion interaction at 4.5 GeV c-1 with the double Maxwell-Boltzmann distribution yields two temperature in the projectile fragmentation region (10 MeV and 40 MeV). This work reports a study on the coherence of pion production for two classes of events-cold (10 MeV) and hot (40 MeV). The data show an interesting observation-in the case of cold events pions are produced coherently in a specific pseudo-rapidity region, whereas pion production is extremely incoherent for hot events in that zone; it is coherent in a different pseudo-rapidity region.

Multiplicity Characteristics of Symmetric and Asymmetric Heavy-Ion Interactions at 4.5 A GeV/c

This letter presents a systematic analysis of multiplicity data in limited regions of phase space in symmetric (12C-C/N/O) and asymmetric (24Mg-Ag/Br) heavy-ion interactions at 4.5A GeV/c. It is observed that in both types of interactions the multiplicity distribution of produced charged particles can be well fitted to the newly prescribed negative binomial (NB) law, the detailed characteristics of which are also investigated. Also, for the first time a universality is observed in the behaviour of entropy production in symmetric and asymmetric nuclear collisions if the incident momentum per nucleon is kept constant.

Analysis ofPT spectrum of projectile fragments in heavy-ion interactions. Identification of collective flow of nuclear matter

SummaryTransverse-momentum data of the projectile fragments are analysed to identify the presence of collective flow of nuclear matter in symmetric (16O-CNO at 2.1A GeV and12C-CNO at 4.5A GeV/c) and asymmetric (24Mg−AgBr at 4.5A GeV/c) heavy-ion interactions, adapting the method proposed by Danielewicz and Odyniec. A comparison of the data with Monte-Carlo-simulated values gives a positive indication of collective flow in each case.

Modified two-sources model and UA5 multiplicity distribution

Abstract A modified two-sources model based on a coherent and chaotic particle production mechanism has been proposed to account for the multiplicity distribution in high energy interactions. The UA5 pp interactions data at 200 GeV and 900 GeV are compared with the model and an extremely good agreement is observed.

Forward-backward multiplicity correlations of pions and protons for different temperature events in heavy-ion interactions

A comparison of transverse momentum (PT) distribution of the alpha particles emitted as projectile fragments from12C-emulsion interaction at 4.5 A GeV/c with double Maxwell-Boltzmann distribution yields two temperatures in the projectile fragmentation region, i.e., 10 MeV and 40 MeV with different reaction mechanisms, thereby giving rise to two classes of events. This work presents a detailed study of the multiplicity characteristics for pions and protons emitted in both forward and backward hemispheres in these two classes of events. The results show some interesting features in these two classes.

Study of transverse momentum spectrum of proton projectile fragments in 4.5A GeV/c12C-Emulsion interactions. Evidence of a single temperature

SummaryThis work reports a study of transverse momentum distribution of relativistic proton fragments emerging from the interaction of12C with nuclear emulsion at 4.5A GeV/c energy. A comparison of transverse momentum spectrum with the Maxwell-Boltzmann distribution reveals a temperature of about 8 MeV. This observation does not agree with the results obtained by a similar analysis with relativistic alpha projectile fragments where there was a clear indication of two different temperatures (10 MeV and 40 MeV).RiassuntoQuesto lavoro riporta uno studio di distribuzione di momento trasverso di frammenti di protoni relativistici che emergono dall’interazione di12C con emulsione nucleare ad energia 4.5A GeV/c. Un confronto dello spettro di momento trasverso con la distribuzione di Maxwell-Boltzmann rivela una temperatura di circa 8 MeV. Questa osservazione non si accorda con i risultati ottenuti da un’analisi simile con frammenti di proiettili alfa relativistici dove è emersa una chiara indicazione di due diverse temperature (10 e 40 MeV).РезюмеВ работе приводятся результаты исследования распределения поперечных импульсов релятивистских протонных фрагментов, образующихся при взаимодействии12С с импульсом 4.5А ГэВ/с с ядерной имульсией. Сравнение спектров поперечных импульсов с распределением Максвелла-Больцмана обнаруживает температуру порядка 8 МэВ. Этот результат не согласуется с данными аналогичного анализа для релятивистских альфа-фрагментов, где были обнаружены две различных температуры (10 МэВ и 40 МэВ).

VALIDITY OF NAKAMURA-KUDO SCALING OF CHARGED PARTICLE PSEUDORAPIDITY DISTRIBUTION IN RELATIVISTIC HEAVY ION INTERACTIONS

This letter reports an analysis of our own emulsion data in terms of charged particle pseudorapidity distribution in the cases of 12C-Ag/Br, 24Mg-Ag/Br at 4.5 A GeV/c, and 16O-Ag/Br at 2.1 A GeV. The data are compared with the analyses using two scaling variables recently proposed by Kenju Mori et al. and Nakamura and Kudo. In all cases the data show a remarkable agreement with the scaling behavior of Nakamura and Kudo. The data obtained for 16O + AgBr interactions at 14.6 A GeV, 60 A GeV, and 200 A GeV are also in favor of the Nakamura-Kudo scaling.