arXiv subjects

G. Van Buren

Publications and source records attributed to G. Van Buren.

8 recordsLinked to original sources

arXiv2005

Correcting for Distortions due to Ionization in the STAR TPC

Physics goals of the STAR Experiment at RHIC in recent (and future) years drive the need to operate the STAR TPC at ever higher luminosities, leading to increased ionization levels in the TPC gas. The resulting ionic space charge introduces field distortions in the detector which impact tracking performance. Further complications arise from ionic charge leakage into the main TPC volume from the high gain anode region. STAR has implemented corrections for these distortions based on measures of luminosity, which we present here. Additionally, we highlight a novel approach to applying the corrections on an event-by-event basis applicable in conditions of rapidly varying ionization sources.

physics.ins-det↗

arXiv2005

The Ratio Sigma0/Lambda at RHIC

While yields of Sigma0 have been measured in many different colliding systems, no measurements exist in high energy nuclear collisions. It also remains unexplored whether the relative yields of Sigma0 and Lambda change in collisions of heavy ions where a dense medium may permit alternate production mechanisms, such as quark coalescence. The STAR detector at RHIC is able to reconstruct the electromagnetic Sigma0 decay into Lambda plus gamma via the weak decay of the Lambda and gamma conversions into e+e- pairs in the detector material. We report here on our measurement of the ratio Sigma0/Lambda in minimum bias 200 GeV d+Au collisions. We also compare the measured ratio to expectations from various models.

nucl-ex↗

arXiv2004

Reconstructing Sigma0 decays in STAR

Typical experimental measurements do not separate the contributions of Sigma state decays from (anti)Lambda yields. An ongoing analysis in STAR is resolving the contribution from excited Sigma states, but the primary contribution comes from electromagnetic decays of the (anti)Sigma0. Photon conversions into e+e- pairs in detector material have been used by STAR to identify photons from pi0 decays. A similar technique has been used here to identify photons from (anti)Sigma0 decays in conjunction with STAR's excellent PID capabilities for finding the associated (anti)Lambda daughters. We report here on progress toward measuring the (anti)Sigma0 yields in various nuclear collisions at RHIC.

nucl-ex↗

arXiv2004

Reeconstructing Sigma0 decays in STAR

Typical comparisons of data from nuclear collisions to particle production models require a caveat for (anti)Lambda yields from experimental inability to separate the contributions of those yields from Sigma state decays. Recent analysis in STAR is leading toward resolving the contribution from excited Sigma states, but the bulk contribution comes from electromagnetic decays of the (anti)Sigma0. In the STAR detector, photon conversions into e+e- pairs in the detector material have been used to identify photons from pi0 decays. A similar technique has been used here to identify photons from (anti)Sigma0 decays in conjunction with STAR's excellent PID capabilities for finding the associated (anti)Lambda daughters. We report here on progress toward measuring the (anti)Sigma0 yields in various nuclear collisions at RHIC.

nucl-ex↗

arXiv2002

Soft Physics in STAR

The STAR Experiment at RHIC is well-suited to making measurements of particle yields from relativistic nuclear collisions in the low transverse momentum, or "soft", regime. We present preliminary results on measurements of pion (0,-,+), kaon (-,+,0short), rho, K*0 + anti-K*0, f0, proton, antiproton, phi, Lambda, anti-Lambda, Xi, anti-Xi, Omega, and anti-Omega from the first two years of physics running at RHIC. An abundance of physics topics can be addressed by these measurements, some of which are discussed here along with the results.

nucl-ex↗

arXiv2002

STAR Strangeness Results from sqrt(s_NN) = 130 GeV Au+Au Collisions (and first results from 200 GeV)

The STAR Experiment at RHIC is capable of a wide variety of measurements of the production of strange hadrons in nuclear collisions. Measurements of the relative production of strange baryons, antibaryons, and kaons can shed light on the baryon densities achieved in these collisions and on the validity of models for production yields. We will present here preliminary results on these measurements at RHIC energies of sqrt(s_NN) = 130 GeV and 200 GeV and discuss comparisons to models.

nucl-ex↗

arXiv1998

A 10 MHz beam counter and a multiplicity detector for the E864 spectrometer

The E864 experiment at BNL requires a beam counter and multiplicity detector system that can perform at an incident beam rate of 10^7 Au ions per second. We have developed and tested a 150 micrometer thick quartz Cherenkov beam counter and a scintillator based multiplicity-trigger counter during the first run of this experiment in 1994. We obtained a time resolution of 78 ps for the beam counter at an incident beam rate 5 x 10^5 Hz and 100 ps at a rate of 1 x 10^7 Hz. Pulse height discrimination is used to obtain a minimum bias and a 10% centrality trigger from the multiplicity detectors. The multiplicity counter has a time resolution of 250 ps.

physics.ins-det↗

arXiv1997

Search for Charged Strange Quark Matter Produced in 11.5 A GeV/c Au + Pb Collisions

We present results of a search for strange quark matter (strangelets) in 11.5 A GeV/c Au+Pb collisions from the 1994 and 1995 runs of experiment E864 at Brookhaven's AGS. We observe no strangelet candidates and set a 90% confidence level upper limit of approximately 3x10**-8 per 10% central interaction for the production of |Z|=1 and |Z|=2 strangelets over a large mass range and with metastable lifetimes of about 50 ns or more. These results place constraints primarily on quark-gluon plasma based production models for strangelets.

nucl-ex↗