Recent results from the NA61/SHINE experiment

Transcription

1 Recent results from the NA6/SHINE experiment Emil Kaptur for the NA6/SHINE collaboration University of Silesia October 7, 5 of 5

2 Outline NA6/SHINE experiment Selected results from energy scan (,,, 8, 58 GeV/c): Inverse slope parameter Step π + mid rapidity multiplicity calculation K/π ratio Horn Comparison with Monte Carlo models Selected results from 7 Be+ 9 Be energy scan (A, A, A, 75A, 5A GeV/c): Forward Energy (FE, E F ) event selection (centrality) Width of the π rapidity distribution Dale Collectivity in 7 Be+ 9 Be mass [GeV /c ].5.5 p + K at GeV/c π de/dx [arb. units] of 5

3 NA6/SHINE detector system JINS 9 () P65 of 5

4 NA6/SHINE D scan goals of 5

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6 y p identified particle spectra in Large acceptance for all particle types p < GeV/c y Beam (58 GeV/c) =.8 y π y K y p y Beam lack of mid rapidity pions, but they are possible 6 of 5 PhD thesis of S. Pulawski

7 Mid rapidity spectra of Kaons [/(GeV/c)] d n dydp + K + X. < y <. 58 GeV/c 8 8 GeV/c 6 GeV/c.9 GeV/c GeV/c p GeV/c [/(GeV/c)] d n dydp K + X. < y <. 58 GeV/c 8 8 GeV/c 6 GeV/c.9 GeV/c GeV/c p [GeV/c] Spectra fitted by: d n dp dy = Fit allows to calculate: he inverse slope parameter S p +m K exp ( p +m K m K Kaon multiplicity in p range not accessible by data ) 7 of 5 PhD thesis of S. Pulawski

8 Inverse slope parameter Step [MeV] K y [MeV] + K y Pb+Pb Au+Au SPS(NA6 ) WORLD() Pb+Pb Au+Au SPS(NA6 ) WORLD() AGS SPS(NA9) AGS SPS(NA9) RHIC LHC(ALICE) RHIC LHC(ALICE) s NN [GeV] s NN [GeV] Energy dependence of the inverse slope parameter of kaon spectra exhibits rapid changes in both and Pb+Pb interactions. Phys.Rev. C69 () 9, SAR: Phys.Rev.C79:99,9; ALICE: PLB 76 () 967, Eur. Phys. J, C () 7:655 PhD thesis of S. Pulawski 8 of 5

9 K π ratio Horn (y ) (y ) K + /π +. /π K.. Pb+Pb Au+Au SPS(NA6 ) WORLD(, π). Pb+Pb Au+Au SPS(NA6 ) WORLD(, π) AGS SPS(NA9) AGS SPS(NA9) RHIC LHC(ALICE) s NN [GeV] RHIC LHC(ALICE) s NN [GeV] he energy dependence of K + /π + ratio in changes at the energy where horn structure is visible in Pb+Pb 9 of 5 Z.Phys. C65 (995) 5 (π), Z.Phys. C7 (996) 556 (K); BRAHMS: Phys.Rev.C7:98,5; ALICE: Eur. Phys. J, C () 7:655, PRL 9, 5 (), PhD thesis of Chojnacki, M.; PhD thesis of S. Pulawski

10 K π ratio in interactions comparison to models (y ) (y ) K + /π +. /π K. NA6/SHINE HSD.5 UrQMD. UrQMD. Pythia 8 EPOS.99.5 NA6/SHINE HSD.5 UrQMD. UrQMD. Pythia 8 EPOS.99 [GeV] s NN.5 [GeV] s NN High precision NA6/SHINE data allows to impose rigorous constraints for MonteCarlo models. Vovchenko et al., PRC 9, 96 (), and private communication. Gavin Salam private communication UrQMD: Prog. Part. Nucl. Phys. (998), J. Phys. G: Nucl. Part. Phys. 5 (999); HSD: Nucl. Phys. A 6, 9 (996), Nucl. Phys. A 6, 7 (998), Phys. Rept. 8, 65 (999); EPOS: Nucl.Phys.Proc.Suppl.96,9, PYHIA: arxiv:.; PhD thesis of S. Pulawski of 5

11 Proton mean transverse mass ] [GeV/c <m > m p [/(GeV/c)] d dydp n 58 GeV/c 8 8 GeV/c 6 GeV/c.9 GeV/c p + X. < y <. GeV/c p [GeV/c].. of 5 p+x NA6;. < y <. HSD.5;. < y <. UrQMD.;. < y <. UrQMD.;. < y <. [GeV] s NN m was calculated using fitted function: d n dp dy = S p +m p exp ( p +m p mp ). m of protons produced in interactions around midrapidity increase slowly with collision energy. Neither UrQMD nor HSD describe this behavior. Vovchenko et al., PRC 9, 96 (), arxiv:8:59, and private communication; UrQMD: Prog. Part. Nucl. Phys. (998), J. Phys. G: Nucl. Part. Phys. 5 (999); HSD: Nucl. Phys. A 6, 9 (996), Nucl. Phys. A 6, 7 (998), Phys. Rept. 8, 65 (999); PhD thesis of S. Pulawski

12 of 5 7 Be+ 9 Be

13 Results sensitivity to Forward Energy (FE) definition he results depend (< 5%) on the definition of forward energy By calculating E F in a larger PSD acceptance, we include more spectators but also more produced particles > <π Be+BegatgAgGeV/c 5.5 8gsmall,gglarge 8gsmall,gglarge 8gsmall,gglarge 6gsmall,gglarge.5 6gsmall,gglarge 6gsmall,gglarge 6gsmall,g8glarge FEgeventgclassgcentre of 5

14 he h analysis method 9% of the negatively charged hadrons produced in 7 Be+ 9 Be interactions are π In the h method a small contribution of other particles (K, p, and decays from Λ and K S) is subtracted based on EPOS model predictions In interactions the de/ dx and tof identification methods cover much narrower region of the phase space than the h method (y ) /π K. NA6/SHINE HSD.5 UrQMD. UrQMD. Pythia 8 EPOS.99.5 (GeV) s NN of 5

15 Double differential spectra of π Analysis done in four FE event classes: 5%, 5 %, 5%, 5 % All quantities were derived from double differential spectra d n dydp or d n dydm corrected for detector effects and feed down from weak decays 5 of 5 [GeV/c] p [GeV/c] p AIGeV/c II5m NA6/SHINEipreliminary BeI+IBeI π +IX y NA6/SHINEpreliminary AGeV/c 5] Be+Be π +X y

16 Rapidity spectra ( 7 Be+ 9 Be, ) 5 energies, FE event classes dn dy NA6/SHINE preliminary A GeV/c A GeV/c Be+Be; 5% Be+Be; 5 % Be+Be; 5% Be+Be; 5 % dn dy NA6/SHINE preliminary A GeV/c A GeV/c Be+Be; 5% Be+Be; 5 % Be+Be; 5% Be+Be; 5 % y y dn dy NA6/SHINE preliminary A GeV/c A GeV/c Be+Be; 5% Be+Be; 5 % Be+Be; 5% Be+Be; 5 % dn dy NA6/SHINE preliminary 8A GeV/c 75A GeV/c Be+Be; 5% Be+Be; 5 % Be+Be; 5% Be+Be; 5 % dn dy NA6/SHINE preliminary 58A GeV/c 5A GeV/c Be+Be; 5% Be+Be; 5 % Be+Be; 5% Be+Be; 5 % 6 of 5 y y y

17 Asymmetry in rapidity spectra dn dy 5 5A GeV/c 5% Be + Be π + X dn dy 5 5A GeV/c 5 % Be + Be π + X 97% y y 86% wo opposite effects influence asymmetry of the spectra: asymmetric system 7 Be projectile on 9 Be target (small effect), centrality selection based on projectile spectators (large effect). Selection of 5% of most central collisions: introduce sharp cut on projectile spectators (N proj S ), fluctuations of target spectators are not explicitly restricted (N targ S Gaussian(x =.7; σ =.)). 7 of 5

18 Width of the rapidity distribution σ y / y beam Be+Be Pb+Pb SPS(NA6 Be+Be) SPS(NA6 ) WORLD() AGS SPS(NA9) σ y calculated from fitted function (two symmetrically displaced Gaussians) σ y related to speed of sound cs Dale Smooth, monotonic behaviour with energy Nonmonotonic behaviour with the system size:.5 NA6/SHINE preliminary. 5 5 s NN [GeV] σ y () y beam < σ y (Pb+Pb) y beam < σ y ( 7 Be+ 9 Be) y beam NA6/SHINE results published in Eur.Phys.J. C7 () 79 8 of 5

19 Effect of isospin asymmetry on σ y /y beam σ /y beam y Be+Be Pb+Pb NA9 NA9 (π+π + )NA9 WORLD() π SPS(NA9) π + SPS(NA6 π NA9 Be+Be) SPS(NA6 π NA6 ).5 NA6/SHINEpreliminary. 5 5 s NN [GeV] he isospin asymmetry affects width of the π rapidity distribution in and Pb+Pb 7 Be+ 9 Be is almost isospin symmetric In collisions rapidity width of π + is larger than width of π distribution he width of the sum of π + and π distributions is in between NA9 π and π + rapidity distributions in collisions from: Eur. Phys. J. C5 (6) 8 9 of 5

20 ransverse mass spectra (, 7 Be+ 9 Be, Pb+Pb) ) ] [(GeV/c d n dydm m ) ] [(GeV/c d n dydm m NA6/SHINE preliminary A GeV/c Pb+Pb; 5% (NA9) NA6/SHINE preliminary A GeV/c Be+Be; 5%; x8 Be+Be; 5 %; x Be+Be; 5%; x Be+Be; 5 % A GeV/c Pb+Pb; 5% (NA9) A GeV/c Be+Be; 5%; x8 Be+Be; 5 %; x Be+Be; 5%; x Be+Be; 5 % m m π [GeV/c ] ) ] [(GeV/c d n dydm m m m π [GeV/c ] ) ] [(GeV/c d n dydm m NA6/SHINE preliminary A GeV/c Pb+Pb; 5% (NA9) NA6/SHINE preliminary A GeV/c Be+Be; 5%; x8 Be+Be; 5 %; x Be+Be; 5%; x Be+Be; 5 % A GeV/c Pb+Pb; 5% (NA9) 75A GeV/c Be+Be; 5%; x8 Be+Be; 5 %; x Be+Be; 5%; x Be+Be; 5 % m m π [GeV/c ] ) ] [(GeV/c d n dydm m m m π [GeV/c ] 58A GeV/c Pb+Pb; 5% (NA9) NA6/SHINE preliminary 5A GeV/c Be+Be; 5%; x8 Be+Be; 5 %; x Be+Be; 5%; x Be+Be; 5 % m m π [GeV/c ] of 5

21 Comparison of transverse mass spectra (energy and system size) Ratio of normalized m spectra at different energies allows to compare shape of the spectra (Be+Be)/() Be+Be π+x.8 NA6/SHINE5preliminary A GeV/c A GeV/c A GeV/c. 75A GeV/c A GeV/c m 5m π [GeV/c ] (Pb+Pb)/() Pb+Pb π+x 58A GeV/c A GeV/c A GeV/c. 8A GeV/c A GeV/c m m π [GeV/c ] 7 Be+ 9 Be data for 5% FE event class Pb+Pb data for 5% or 7.5% most central interactions of 5 NA6/SHINE results published in Eur.Phys.J. C7 () 79

22 Comparison of transverse mass spectra )Be+Be)/)) Be+Be π+x 5A GeV/c 75A GeV/c A GeV/c A GeV/c A GeV/c NA6/SHINE9preliminary m π [GeV/c ] m From m m π >. GeV/c the ratio increases with beam momentum Up to m m π <. GeV/c the ratio decreases with beam momentum he beam momentum dependence of the ratio observed in 7 Be+ 9 Be is not visible in Pb+Pb collisions (previous slide) he shape of the ratio indicates the presence of radial collective flow in 7 Be+ 9 Be he energy dependence of the ratio suggests that the radial flow increases with the collision energy of 5

23 Summary he data on pion, kaon and proton production properties in was presented, as well as negative pion spectra from 7 Be+ 9 Be at five beam momenta (A, A, A, 75A, 5A GeV/c). data is unexpectedly interesting. Even in the energy dependence of K + /π + and inverse slope parameter exhibits rapid changes in the SPS energy range. High precision NA6/SHINE data present a challenge for models and should allow their improvement. he isospin effects play a large role in data, the effects will be studied in detail to compare with 7 Be+ 9 Be data. he shape of transverse mass spectra shows energy dependence that is different in 7 Be+ 9 Be and. he radial flow in 7 Be+ 9 Be might increase with collision energy. of 5

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25 Inverse slope parameter system size and energy dependence [MeV] Pb + Pb; central (NA9) Be + Be; central p + p NA6/SHINE Preliminary [GeV] s NN Pb+Pb much higher than Effect of radial flow 7 Be+ 9 Be points in between Pb+Pb and Note: Inverse slope parameter in A+A collisions is very sensitive to fit range and size of the rapidity bin. 5 of 5