Multiparticle production of doubly charged fragments in the fragmentation of relativistic nuclei
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EMENTARY PARTICLES AND FIELDS Experiment
Multiparticle Production of Doubly Charged Fragments in the Fragmentation of Relativistic Nuclei F. G. Lepekhin* Petersburg Nuclear Physics Institute, Russian Academy of Sciences, Gatchina, 188350 Russia Received February 22, 2008; in final form, June 7, 2008
Abstract—Features of angular distributions of events involving two or more doubly charged fragments of relativistic nuclei 22 Ne, 24 Mg, 14 N, 11 B, and 10 B in photoemulsions are studied. It is found that, in all cases, with the exception of the case of the intermediate-state decay 8 Be → 2α, the fragments in these events are independent of one another. The inclusive angular distributions of fragments of relativistic nuclei 22 Ne for events in which the number of particles ranges between one and five are identical. Thus, the emission angle of each fragment of a relativistic nucleus does not depend either on other fragments or on the presence or absence of product particles and target-nucleus fragments in an event. PACS numbers: 25.10.+s DOI: 10.1134/S1063778809020069
1. INTRODUCTION At the present time, there is a vast body of experimental data on the fragmentation of relativistic nuclei ranging between lithium and lead, having energies between 1.2 and 200 GeV, and interacting with photoemulsion nuclei [1–8]. Doubly charged fragments stand out among all possible fragments. The cross sections for their production are large, and their identification is highly reliable. While singly charged particles appearing in a narrow cone of secondaries may involve not only ions but also product pions, all traces featuring quadruple ionization are exclusively helium isotopes. As was shown in [3], the isotope 6 He can also be separated in the fragmentation of relativistic nuclei 11 B. The channel 10 B → 8 Be + all → 2α + all was selected in [2] in the fragmentation of 10 B nuclei, and the fact of a cascade fragmentation of a relativistic nucleus was established in this way. In [8], a 12 C∗ intermediate state decaying to three alpha particles was assumed to contribute to the fragmentation channel 14 N → 3α + all, but no piece of quantitative evidence was obtained for this there. The problem of the existence of resonance states formed by three or more alpha particles is of interest. In view of this, almost the same events as those that were found in the Laboratory of High Energies at the Joint Institute for Nuclear Research (JINR Dubna) in scanning along a track were revisited in the present study by applying the same procedure for measuring angles as that which was employed in studying the *
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fragmentation of relativistic nuclei in [2, 3, 5]. The results obtained in this way are discussed below. In the present article, particular attention is given to experimental data on the fragmentation of relativistic nuclei 22 Ne having a momentum of 4.1 GeV/c per nucleon and interacting with photoemulsion nuclei [1]. The database of 4309 respective events can be found in [9]. The fragmentation of relativistic neon nuclei w
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