Abstract
Double differential cross sections of positively charged pions and protons have been measured in nuclear collisions of mass-symmetric systems (Ne+NaF, Ni+Ni, Au+Au, Bi+Pb) at incident energies between 0.8 and 1.8 AGeV as a function of the centrality of the reaction. Using a magnetic spectrometer pions and protons were detected with laboratory angles between 40 and 48 degrees, and with momenta up to about 1400 MeV/c. This setting allows for the study of pions and protons emitted close to midrapidity. The center-of-mass pion spectra deviate from a Boltzmann distribution. The inverse slope parameters of the high-energetic pions are smaller than those of the proton spectra and they exhibit a weaker centrality dependence. A scenario is presented where the shape of the pion spectra reflects the decay kinematics of nucleonic resonances embedded in the thermal and the collective motion of the nucleons in the reaction zone. The number of emitted pions per participating nucleon is higher for light than for heavy mass systems. For a given mass system, the total pion multiplicity increases linearly with the number of participating nucleons, whereas the multiplicity of high-energy pions increases more than linearly. This result is consistent with a scenario where the high-energy pions are produced in multiple energetic baryon-baryon collisions occurring in the high-density phase of the collision.
Similar content being viewed by others
References
S. Nagamiya et al., Phys. Rev. C 24, 971 (1981)
R. Brockmann et al., Phys. Rev. Lett., 53, 2012 (1984)
R. Stock, Phys. Rep. 135, 259 (1986)
S. Nagamiya, Phys. Rev. Lett. 49, 1383 (1982)
P. Braun-Munzinger, J. Stachel, J. P. Wessels, N. Xu, Phys. Lett. B 344, 43 (1995)
S. Hayashi et al., Phys. Rev. C 38, 1229 (1988)
S. Backovic et al., Phys. Rev. C 46, 1501 (1992)
O. Schwalb et al., Phys. Lett. B 321, 20 (1994)
C. Miintz et al., Z. Phys. A 352, 175 (1995); C. Müntz, PhD Thesis (1993), Technische Hochschule Darmstadt, Germany, GSI report 93-41 (ISSN 0171-4546)
P. Danielewicz, Phys. Rev. C 51, 716 (1995)
P. Senger et al., Nucl. Instr. Meth. A 327, 393 (1993)
P. Baltes et al., GSI Scientific Report 1993, p. 285
H. Stelzer, Nucl. Instr. Meth. A 310, 103 (1991)
D. Miśkowiec et al., Nucl. Instr. Meth. A 350, 174 (1994)
W. Ahner et al., Z. Phys. A 341, 123 (1991)
D. Brill et al., Phys. Rev. Lett. 71, 336 (1993); D. Brill et al., Z. Phys. A 355, 61 (1996); D. Brill, PhD Thesis (1993), University of Frankfurt, Germany, GSI report 93-36 (ISSN 0171-4546)
R. Brun, F. Bouyant, M. Maire, A.C. McPherson, P. Zanarini, CERN Publication DD/EE/84-1
B. J. Ver West, R. A. Arndt, Phys. Rev. C 25, 1979 (1982)
J.W. Harris et al., Phys. Rev. Lett. 58, 463 (1987)
D. Ashery et al., Phys. Rev. C 23, 2173 (1981)
D. Miskowiec et al., Phys. Rev. Lett. 72, 3650 (1994); D. Miśkowiec, PhD Thesis (1991), Jagiellonian University Cracow, Poland
H.H. Gutbrod et al., Phys. Rev. C 42, 640 (1990)
G. Fai and J. Randrup, Comp. Phys. Communication 42, 385 (1986)
K.G.R. Doss et al., Mod. Phys. Lett. A3, 849 (1988)
S. A. Bass, C. Hartnack, H. Stöcker and W. Greiner, Phys. Rev. C50, 2167 (1994)
S. A. Bass, M. Hofmann, C. Hartnack, H. Stöcker and W. Greiner, Phys. Lett. B335, 289 (1994)
J. Cugnon et al., Nucl. Phys. A 379, 553 (1982)
B.A. Li and W. Bauer, Phys. Rev. C 44, 450 (1991); B.A. Li, Nucl. Phys. A 552, 605 (1993)
W. Ehehalt et al., Phys. Rev. C 47, R2467 (1993)
P. J. Siemens and J. O. Rasmussen, Phys. Rev. Lett 42, 880 (1979)
M. A. Lisa et al., Phys. Rev. Lett. 75, 2662 (1995); M.D. Partlan et al., Phys. Rev. Lett. 75, 2100 (1995)
Y. Kitazoe et al., Phys. Lett. B 166, 35 (1986)
B.A. Li et al., Phys. Rev. C 52, 2037 (1995)
M. Hofmann et al., GSI Scientific Report 1994, p. 119
R. Averbeck et al., GSI Scientific Report 1994, p. 80 36. M. Cieślak, PhD Thesis (1995), Jagiellonian University Cracow, Poland; and to be published
J. Aichelin et al., Phys. Rev. Lett. 58, 1926 (1987)
W. Cassing et al., Phys. Rep. 188, 363 (1990)
C. Hartnack et al., Nucl. Phys. A 580, 643 (1994)
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Müntz, C., Baltes, P., Oeschler, H. et al. Pion production in mass- symmetric heavy ion collisions at 0.8–1.8 AGeV. Z Phys A - Particles and Fields 357, 399–409 (1997). https://doi.org/10.1007/s002180050259
Received:
Revised:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s002180050259