اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدMeasuring centrality with slow protons in proton-nucleus collisions at the AGS
95
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
Experiment 910 has measured slow protons and deuterons from collisions of 18 GeV/c protons with Be, Cu, and Au targets at the BNL AGS. These correspond to the ``grey tracks first observed in emulsion experiments. We report on their momentum and angular distributions and investigate their use in measuring the centrality of a collision, as defined by the mean number of projectile-nucleon interactions. The relation between the measured Ngrey and the mean number of interactions, nu(Ngrey), is studied using several simple models, one newly proposed, as well as the RQMD event generator. RQMD is shown to reproduce the Ngrey distribution, and exhibits a dependence of Ngrey on centrality that is similar to the behavior of the simple models. We find a strong linear dependence of average Ngrey on nu, with a constant of proportionality that varies with target. For the Au target, we report a relative systematic error for extracting nu(Ngrey) that lies between 10% and 20% over all Ngrey.
قيم البحث
اقرأ أيضاً
Asymmetric peaks in the pion-proton correlation functions were observed. Such an asymmetry indicates a displacement between the sources of the two particle species.
Inclusive and semi-inclusive measurements are presented for antiproton ($bar{p}$) production in proton-nucleus collisions at the AGS. The inclusive yields per event increase strongly with increasing beam energy and decrease slightly with increasing t
arget mass. The $bar{p}$ yield in 17.5 GeV/c p+Au collisions decreases with grey track multiplicity, $N_g$, for $N_g>0$, consistent with annihilation within the target nucleus. The relationship between $N_g$ and the number of scatterings of the proton in the nucleus is used to estimate the $bar{p}$ annihilation cross section in the nuclear medium. The resulting cross section is at least a factor of five smaller than the free $bar{p}-p$ annihilation cross section when assuming a small or negligible formation time. Only with a long formation time can the data be described with the free $bar{p}-p$ annihilation cross section.
Directed flow of antiprotons is studied in Au+Au collisions at a beam momentum of 11.5A GeV/c. It is shown that antiproton directed flow is anti-correlated to proton flow. The measured transverse momentum dependence of the antiproton flow is compared with predictions of the RQMD event generator.
The NA60 experiment has studied J/psi production in p-A collisions at 158 and 400 GeV, at the CERN SPS. Nuclear effects on the J/psi yield have been estimated from the A-dependence of the production cross section ratios sigma_{J/psi}^{A}/sigma_{J/psi
}^{Be} (A=Al, Cu, In, W, Pb, U). We observe a significant nuclear suppression of the J/psi yield per nucleon-nucleon collision, with a larger effect at lower incident energy, and we compare this result with previous observations by other fixed-target experiments. An attempt to disentangle the different contributions to the observed suppression has been carried out by studying the dependence of nuclear effects on x_2, the fraction of nucleon momentum carried by the interacting parton in the target nucleus.
The production of non-phi K+K- pairs by protons of 2.83 GeV kinetic energy on C, Cu, Ag, and Au targets has been investigated using the COSY-ANKE magnetic spectrometer. The K- momentum dependence of the differential cross section has been measured at
small angles over the 0.2--0.9 GeV/c range. The comparison of the data with detailed model calculations indicates an attractive K- -nucleus potential of about -60 MeV at normal nuclear matter density at a mean momentum of 0.5 GeV/c. However, this approach has difficulty in reproducing the smallness of the observed cross sections at low K- momenta.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
