arXiv subjects

C. Pinkenburg

Publications and source records attributed to C. Pinkenburg.

12 recordsLinked to original sources

arXiv2024

The sPHENIX Micromegas Outer Tracker

The sPHENIX Time Projection Chamber Outer Tracker (TPOT) is a Micromegas based detector. It is a part of the sPHENIX experiment that aims to facilitate the calibration of the Time Projection Chamber, in particular the correction of the time-averaged and beam-induced distortions of the electron drift. This paper describes the detector mission, setup, construction, installation, commissioning and performance during the first year of sPHENIX data taking.

physics.ins-det↗

arXiv2018

Design and Beam Test Results for the sPHENIX Electromagnetic and Hadronic Calorimeter Prototypes

The super Pioneering High Energy Nuclear Interaction eXperiment (sPHENIX) at the Relativistic Heavy Ion Collider (RHIC) will perform high precision measurements of jets and heavy flavor observables for a wide selection of nuclear collision systems, elucidating the microscopic nature of strongly interacting matter ranging from nucleons to the strongly coupled quark-gluon plasma. A prototype of the sPHENIX calorimeter system was tested at the Fermilab Test Beam Facility as experiment T-1044 in the spring of 2016. The electromagnetic calorimeter (EMCal) prototype is composed of scintillating fibers embedded in a mixture of tungsten powder and epoxy. The hadronic calorimeter (HCal) prototype is composed of tilted steel plates alternating with plastic scintillator. Results of the test beam reveal the energy resolution for electrons in the EMCal is $2.8\%\oplus~15.5\%/\sqrt{E}$ and the energy resolution for hadrons in the combined EMCal plus HCal system is $13.5\%\oplus 64.9\%/\sqrt{E}$. These results demonstrate that the performance of the proposed calorimeter system satisfies the sPHENIX specifications.

physics.ins-det↗

arXiv2004

Search for the $\barΘ^- \to $ K$^-$ $\bar{n}$ with PHENIX

The PHENIX experiment at RHIC should be sensitive to decays of the the anti--pentaquark $\barΘ^-$ via the K$^-$ $\bar{n}$ channel. Charged kaons can be identified using the standard tracking and time of flight up to a momentum of 1.5 GeV/c. Anti--neutron candidates are detected via their annihilation signal in the highly segmented electromagnetic calorimeter (EMCal). In order to assess the quality of the anti--neutron identification we reconstruct the $\barΣ \to \bar{n}π$. As an additional crosscheck the invariant mass of K$^+$ $\bar{n}$ is reconstructed where no resonance in the pentaquark mass range is expected. At the present time no enhancement at the expected pentaquark mass is observed in dAu collisions at $\sqrt{s_{NN}} = 200 GeV.

nucl-ex↗

arXiv2002

Longitudinal Flow of Protons from 2-8 AGeV Central Au+Au Collisions

Rapidity distributions of protons from central $^{197}$Au + $^{197}$Au collisions measured by the E895 Collaboration in the energy range from 2 to 8 AGeV at the Brookhaven AGS are presented. Longitudinal flow parameters derived using a thermal model including collective longitudinal expansion are extracted from these distributions. The results show an approximately linear increase in the longitudinal flow velocity, $<βγ>_{L}$, as a function of the logarithm of beam energy.

nucl-ex↗

arXiv2001

Production and collective behavior of strange particles in Au + Au collisions at 2--8 AGeV

The E895 experiment at the AGS measured strange particle production and collective behavior in Au+Au collisions between 2--8 AGeV. The production of $Λ$ Baryons and K$^0$ Mesons as function of energy rises smoothly and exhibits a nonlinear impact parameter dependence. Neutral and positively charged Kaons exhibit a strong anti-flow behavior. $Λ$ Baryons show a smaller flow signal than protons.

nucl-ex↗

arXiv2001

Laying the groundwork at the AGS: Recent results from experiment E895

The E895 Collaboration at the Brookhaven AGS has performed a systematic investigation of Au+Au collisions at 2-8 AGeV, using a large-acceptance Time Projection Chamber. In addition to extensive measurements of particle flow, spectra, two-particle interferometry, and strangeness production, we have performed novel hybrid analyses, including azimuthally-sensitive pion HBT, extraction of the six-dimensional pion phasespace density, and a first measurement of the Lambda-proton correlation function.

nucl-ex↗

arXiv2001

Anti-flow of K$^0_s$ Mesons in 6 AGeV Au + Au Collisions

We have measured the sideward flow of neutral strange ($K^0_s$) mesons in 6 AGeV Au + Au collisions. A prominent anti-flow signal is observed for an impact parameter range (b $\lesssim 7$ fm) which spans central and mid-central events. Since the $K^0_s$ scattering cross section is relatively small in nuclear matter, this observation suggests that the in-medium kaon vector potential plays an important role in high density nuclear matter.

nucl-ex↗

arXiv2001

Directed Flow of $Λ$-Hyperons in 2-6 AGeV Au+Au Collisions

Directed flow measurements for $Λ$-hyperons are presented and compared to those for protons produced in the same Au+Au collisions (2, 4, and 6 AGeV; $b < 5 - 6$ fm). The measurements indicate that $Λ$-hyperons flow consistently in the same direction and with smaller magnitudes than those of protons. Such a strong positive flow [for $Λ$s] has been predicted in calculations which include the influence of the $Λ$-nucleon potential. The experimental flow ratio $Λ$/p is in qualitative agreement with expectations ($\sim 2/3$) from the quark counting rule at 2 AGeV but is found to decrease with increasing beam energy.

nucl-ex↗

arXiv2000

Azimuthal Dependence of Pion Interferometry at the AGS

Two-pion correlation functions, measured as a function of azimuthal emission angle with respect to the reaction plane, provide novel information on the anisotropic shape and orientation of the pion-emitting zone formed in heavy ion collisions. We present the first experimental determination of this information, for semi-central Au+Au collisions at 2-6 AGeV. The source extension perpendicular to the reaction plane is greater than the extension in the plane, and tilt of the pion source in coordinate space is found to be opposite its tilt in momentum space.

nucl-ex↗

arXiv1999

Elliptic Flow: Transition from out-of-plane to in-plane Emission in Au + Au Collisions

We have measured the proton elliptic flow excitation function for the Au + Au system spanning the beam energy range 2 -- 8 AGeV. The excitation function shows a transition from negative to positive elliptic flow at a beam energy, $E_{tr} \sim$ 4 AGeV. Detailed comparisons with calculations from a relativistic Boltzmann-equation are presented. The comparisons suggest a softening of the nuclear equation of state (EOS) from a stiff form (K \sim 380 MeV) at low beam energies (E_{Beam} \le 2 AGeV) to a softer form (K \sim 210 MeV) at higher energies (E_{Beam} \ge $ 4 AGeV) where the calculated baryon density $ ρ\sim 4 ρ_0$.

nucl-ex↗

arXiv1998

Disappearance of Elliptic Flow: A New Probe for the Nuclear Equation of State

Using a relativistic hadron transport model, we investigate the utility of the elliptic flow excitation function as a probe for the stiffness of nuclear matter and for the onset of a possible quark-gluon-plasma (QGP) phase-transition at AGS energies 1 < E_Beam < 11 AGeV. The excitation function shows a strong dependence on the nuclear equation of state, and exhibits characteristic signatures which could signal the onset of a phase transition to the QGP.

nucl-th↗

arXiv1997

Abundance of Delta Resonances in 58Ni+58Ni Collisions between 1 and 2 AGeV

Charged pion spectra measured in 58Ni-58Ni collisions at 1.06, 1.45 and 1.93 AGeV are interpreted in terms of a thermal model including the decay of Delta resonances. The transverse momentum spectra of pions are well reproduced by adding the pions originating from the Delta-resonance decay to the component of thermal pions, deduced from the high transverse momentum part of the pion spectra. About 10 and 18% of the nucleons are excited to Delta states at freeze-out for beam energies of 1 and 2 AGeV, respectively.

nucl-ex↗