Rho Meson Diffraction off Au Nuclei Debbe, R
Journal of physics. Conference series,
01/2012, Letnik:
389, Številka:
1
Journal Article, Conference Proceeding
Recenzirano
Odprti dostop
The STAR Ultra Peripheral Collisions program has collected a substantial sample of ρ mesons and for the first time at RHIC energies it has been able to extract the distribution of momentum transfert ...t from diffractive elastic scattering off the Au ion. The resulting difraction pattern is consistent with coherent scattering off a nuclear object the size of the Au nuclei. Measurements of this nature can offer insights and guidance to the ongoing preparations for the new electron ion programs.
Measurements of identified single particle distributions in d
+
Au collisions at
s
NN
=
200
GeV
at the RHIC collider are described. The dependence of these distributions on the centrality of the ...collisions, as well as the rapidity of the detected particles are emphasized in this report.
The BRAHMS ring imaging Cherenkov detector Debbe, R.; Jørgensen, C.E.; Olness, J. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
01/2007, Letnik:
570, Številka:
1
Journal Article
Recenzirano
Odprti dostop
A Ring Imaging Cherenkov detector built for the BRAHMS experiment at the Brookhaven RHIC is described. This detector has a high index of refraction gas radiator. Cherenkov light is focused on a ...photo-multiplier based photon detector with a large spherical mirror. The combination of momentum and ring radius measurement provides particle identification from 2.5 to 35
GeV/
c for pions and kaons and well above 40
GeV/
c for protons during runs that had the radiator index of refraction set at
n
-
1
=
1700
×
10
-
6
.
We present a measurement of π−/π+, K−/K+ and p¯/p from p+p collisions at s=200 GeV over the rapidity range 0<y<3.4. For pT<2.0 GeV/c we see no significant transverse momentum dependence of the ...ratios. All three ratios are independent of rapidity for y≲1.5 and then steadily decline from y∼1.5 to y∼3. The π−/π+ ratio is below unity for y>2.0. The p¯/p ratio is very similar for p+p and 20% central Au+Au collisions at all rapidities. In the fragmentation region the three ratios seem to be independent of beam energy when viewed from the rest frame of one of the protons. Theoretical models based on quark–diquark breaking mechanisms overestimate the p¯/p ratio up to y≲3. Including additional mechanisms for baryon number transport such as baryon junctions leads to a better description of the data.
The RHIC high energy collision of species ranging from p+p, p(d)+A to A+A provide access to the
small-x component of the hadron wave function. The RHIC program has brought renewed interest in that ...subject with its ability to reach values of the parton momentum fraction smaller than 0.01 with studies of particle production at high rapidity. Furthermore, the use of heavy nuclei in the p(d)+A collisions facilitates the study of saturation effects in the gluonic component of the nuclei because the appropriate scale for that regime grows as
A
1
3
. We review the experimental results of the RHIC program that have relevance to
small-x emphasizing the physics extracted from d+Au collisions and their comparison to p+p collisions at the same energy.
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