Antiproton Production In Nucleus-nucleus Collisions Research Articles

Mass dependence of antiproton production in nucleus-nucleus collisions at 3.65 GeV/nucleon

Antiproton production cross-sections have been measured for p+C, C+C, C+Cu and C+Pb collisions at 3.65 GeV/nucleon.\(\bar p\) laboratory momentum and angle are 0.8 GeV/c and 24°. The target mass dependence parameter is found to be 0.43±0.1. A strong increase in antiproton yield is observed from p+C, d+C to C+C collisions. Projectile mass parameter is 1.2±0.2 for d+C to C+C. The construction and calibration of APAKI, an annihilation detector for\(\bar p\) identification, are also described.

Subthreshold antiproton production in nucleus-nucleus collisions.

Antiproton production in nucleus-nucleus collisions at energies below the threshold for its production from the nucleon-nucleon interaction in free space is studied in the relativistic Vlasov-Uehling-Uhlenbeck model. The antiproton self-energies in the medium are obtained in the mean-field approximation from the G-parity transformation of the nucleon self-energies. Due to the decrease of antiproton mass in the medium as a result of the attractive scalar mean field, there is an enhanced production of primordinal antiprotons which are, however, mostly annihilated by nucelons as they propagate through the matter. The calculated final antiproton momentum spectrum is seen to agree reasonably with the experimental data.

Antikaon and antiproton production in nucleus-nucleus collisions with relativistic quantum molecular dynamics

In this paper we study the antikaon and antiproton productions in nucleus-nucleus collisions at intermediate bombarding energies. Relativistic quantum molecular dynamics (RQMD) is used to simulate dynamical evolution of nuclear reactions and generate stochastic baryon-baryon collisions where antikaons and antiprotons might be produced. The antikaons and antiprotons are assumed to be created predominantly in processes such as B 1+ B 2→ N+ N+ K+ K and B 1+ B 2→ N+ N+ p+ p . We compare our results obtained with different nuclear equations of state, with and without the absorption of antikaons and antiprotons by surrounding the nucleons; and different parametrizations for the elementary production cross section in the baryon-baryon collision. The theoretical results are also compared with the available experimental data.

Subthreshold antiproton production in nucleus-nucleus collisions.

Antiproton production in nucleus-nucleus collisions at energies below the threshold for its production from the nucleon-nucleon interaction in free space is studied in the relativistic Vlasov-Uehling-Uhlenbeck model. The antiproton self-energies in the medium are obtained in the mean-field approximation from the G-parity transformation of the nucleon self-energies. Due to the decrease of antiproton mass in the medium as a result of the attractive scalar mean field, there is an enhanced production of primordinal antiprotons which are, however, mostly annihilated by nucelons as they propagate through the matter. The calculated final antiproton momentum spectrum is seen to agree reasonably with the experimental data.

Subthreshold antiproton production in 28Si+28Si collisions at 2.1 GeV/nucleon.

We report on the first observation of subthreshold antiproton production in nucleus-nucleus collisions. This measurement was made for the system /sup 28/Si+/sup 28/Si at a bombarding energy of 2.1 GeV/nucleon (kinetic energy per NN pair in the c.m. frame /similar to/850 MeV). A differential cross section d/sup 2/sigma/dP d ..cap omega.. of 80 +- 40 nb/sr (GeV/c) was measured for p-bar production at 1.9 GeV/c and 0/sup 0/. This result is 3 orders of magnitude larger than that predicted by a calculation incorporating internal motion of the nucleons in the colliding nuclei.