Cumulative {pi}-Mesons in {}^{{12}}{C}{+}{}^{{9}}Be-Interactions at 3.2 GeV/Nucleon

B M Abramov,Yu A Borodin,M A Martemianov,A P Krutenkova,V V Kulikov,S A Bulychjov,E N Turdakina,M A Matsyuk,M Baznat,I A Dukhovskoy

doi:10.1134/s1063778821040037

B M Abramov, Yu A Borodin + Show 8 more

Open Access

https://doi.org/10.1134/s1063778821040037

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Abstract

In the FRAGM experiment at the heavy-ion accelerator-accumulator complex ITEP-TWA, yields of cumulative charged pi mesons have been measured in a fragmentation of carbon ions with the energy of 3.2 GeV/nucleon on a beryllium target. The momentum spectra of pi mesons cover four orders of the invariant cross section magnitude. They demonstrate the exponential fall with increasing energy. The measured inverse slope parameter is compared with similar measurements in nucleon–nucleus interactions and ion–ion collisions at lower energies. The energy dependence of the ratio of the yields of negative to positive pi mesons is presented. This dependence is discussed in a connection with Coulomb and isotopic effects. The obtained data are compared with predictions of several ion–ion interaction models.

Highlights

An understanding of mechanisms of cumulative processes [1, 2], kinematically forbidden in interactions of free nucleons, remains the unsolved problem of relativistic nuclear physics for many decades
In the FRAGM experiment, the π+ and π− meson yields at the angle of 3.5◦ were measured in the fragmentation of carbon nuclei with the energy of
The π meson kinetic energy spectra in the rest frame of the incident carbon nucleus are well described by an exponent with the inverse slope parameter or the cumulative temperature Tc = 51 ± 1 MeV

Summary

INTRODUCTION

An understanding of mechanisms of cumulative processes [1, 2], kinematically forbidden in interactions of free nucleons, remains the unsolved problem of relativistic nuclear physics for many decades. A large attention is paid to a phenomenologically accurate description of nucleus– nucleus interactions. In this direction, a significant amount of simulation codes of nucleus–nucleus interactions was developed. A production of π mesons, including cumulative ones, is the main inelastic process at intermediate energies. This production occurs mainly through multiple mesonic and baryonic resonances. All aforementioned models treat nucleus–nucleus interactions as a sequence of general processes which include intranuclear cascade, production of excited prefragments and their deexcitation through Fermi breakup, fission and evaporation. The useful information on this topic can be found in the Geant Physics Manual [14]

THE EXPERIMENT

PROTON AND π MESON MOMENTUM SPECTRA

Findings

CONCLUSIONS