Measurements of pi ^- production in ^7Be + ^9Be collisions at beam momenta from 19A to 150A,text{ GeV }!/!c in the NA61/SHINE experiment at the CERN SPS

A Acharya,V A Kireyeu,W Bryliński,F Guber,K Kadija,S Puławski,M Baszczyk,D Larsen,M Naskręt,D Veberič,A Krasnoperov,T Šuša,L Turko,A Rybicki,D Röhrich,O Wyszyński,W Kucewicz,V Golovatyuk,I Selyuzhenkov,K Grebieszkow,S Sadhu,A Wickremasinghe,Z Włodarczyk,M Gaździcki,A Aduszkiewicz,S Kowalski,M Maćkowiak-Pawłowska,T Czopowicz,K Łojek,M Posiadała-Zezula,M Deveaux,A Kurepin,M Golubeva,R Ulrich,M Roth,K Schmidt,S N Igolkin,J Puzović,H Ströbele,Y Nagai,S Mrówczyński,A Dmitriev,M Słodkowski,R Płaneta,P Dorosz,Ł Mik,R Renfordt,V Matveev,M Ćirković,V Ozvenchuk,H J Mathes ,E Kashirin,M Buryakov,D S Prokhorova,A Blondel,P Staszel,V Lyubushkin ,A Korzenev,Б Popov ,R Engel,P Seyboth,Z Fodor,O Golosov,M Rumyantsev,E Rondio,G Stefanek,H Cherif,В Терещенко ,T Antičić ,D Tefelski,A D Marino,S Bhosale,Evgeny Andronov ,V Kovalenko ,D Pszczel,O Petukhov,M Kozieł ,V P Klochkov ,E D Zimmerman,V Paolone,A Malakhov ,M Unger,J Cybowska,S Johnson ,M Kuich,D Kolev,A Yu Seryakov,H Adhikary,M Deliyergiyev,K Márton ,K Wôjcik ,A Rustamov,G L Melkumov,A Damyanova,Adam Bzdak ,A V Brandin ,M Csanád ,V Vechernin ,R Tsenov,A Marcinek,В И Колесников ,S V Morozov ,Г Феофилов ,B Messerly,B Pórfy ,T Matulewicz,Н Каргин ,M Ravonel,A Sadovsky,А А Гарибов ,B T Rumberger,M M Kielbowicz ,M Rybczyński ,Á László ,A O Merzlaya,M Bogomilov,Ф Ф Валиев ,J Steṕaniak ,Maciej Piotr Lewicki ,A Toia,V Babkin,M Strikhanov,L Fields,W Dominik,B Maksiak,S Ilieva,A Bravar,O Busygina,N Davis,A Haesler,J Brzychczyk,P Podlaski,A Ivashkin,J Dumarchez,A Taranenko,D Uzhva,Z Majka,A Tefelska,K K Allison,T Lazareva ,R Zwaska

doi:10.1140/epjc/s10052-020-08514-6

Abstract

The NA61/SHINE collaboration studies at the CERN Super Proton Synchrotron (SPS) the onset of deconfinement in hadronic matter by the measurement of particle production in collisions of nuclei with various sizes at a set of energies covering the SPS energy range. This paper presents results on inclusive double-differential spectra and mean multiplicities of pi ^{-} mesons produced in the 5% most central^7Be + ^9Be collisions at beam momenta of 19A, 30A, 40A, 75A and 150A,text{ GeV }!/!c obtained by the so-called h^- method which does not require any particle identification. The shape of the transverse mass spectra differs from the shapes measured in central Pb + Pb collisions and inelastic p+p interactions. The normalized width of the rapidity distribution decreases with increasing collision energy and is in between the results for inelastic nucleon–nucleon and central Pb + Pb collisions. The mean multiplicity of pions per wounded nucleon in central^7Be + ^9Be collisions is close to that in central Pb + Pb collisions up to 75A,text{ GeV }!/!c. However, at the top SPS energy the result lies between those for nucleon–nucleon and Pb + Pb interactions. The results are discussed in the context of predictions for the onset of deconfinement at the CERN SPS collision energies.

Highlights

This paper presents measurements of inclusive spectra and mean multiplicities of π − mesons produced in central 7Be +91B50e AcoGlleiVsi/ocn(s√ast NbNea=m momenta of 19A, 6.1, 7.6, 8.8, 11.930 A, 40 A, 75A and and 16.8 GeV) performed by the NA61/SHINE collaboration
9.51 2.4 1.32 0.7 1.009 (iii) total number of reconstructed points on the track should be greater than 15, (iv) sum of the number of reconstructed points in Vertex TPCs (VTPC)-1 and VTPC-2 should be greater than 15 or greater than 4 in the GTPC, (v) the distance between the track extrapolated to the interaction plane and the interaction point should be smaller than 4 cm in the horizontal plane and 2 cm in the vertical plane, (vi) electron tracks were excluded by a cut on the measured particle energy loss dE/dx in the Time Projection Chambers (TPC)
In order to determine the mean multiplicity of primary π − mesons produced in central Be + Be collisions a set of corrections was applied to the extracted raw results

Summary

Introduction

This paper presents measurements of inclusive spectra and mean multiplicities of π − mesons produced in central 7Be +91B50e AcoGlleiVsi/ocn(s√ast NbNea=m momenta of 19A, 6.1, 7.6, 8.8, 11.930 A, 40 A, 75A and and 16.8 GeV) performed by the NA61/SHINE collaboration. The first goal of the programme is motivated by the observation of rapid changes of hadron production properties in central Pb + Pb collisions at about 30A GeV/c by the NA49 experiment [2,3] – a sharp peak in the kaon to pion ratio (“horn”), the start of a plateau in the inverse slope parameter for kaons (“step”), and a steepening of the increase of pion production per wounded nucleon with increasing collision energy (“kink”) These findings were predicted and interpreted as the onset of deconfinement [4,5]. This is of particular importance when data on proton-proton, neutron-proton and neutron-neutron are not available to construct the nucleon– nucleon reference [18]

Methods

Results

Discussion

Conclusion