T. Ljubicic

The forward time projection chamber in STAR

Two cylindrical forward TPC detectors are described which were constructed to extend the phase space coverage of the STAR experiment to the region 2.5 < |�| < 4.0. For optimal use of the available space and in order to cope with the high track density of central Au+Au collisions at RHIC, a novel design was developed using radial drift in a low diffusion gas. From prototype measurements a 2-track resolution of 1 - 2 mm is expected.

Search for hadronic axions using axioelectric effect

Abstract We made a search for hadronic axions which could be emitted from the Sun in M1 transitions between the first 14.4 keV thermally excited and the ground state in 57Fe, and absorbed in the HPGe detector by axioelectric effect. An upper limit on hadronic axion mass of 400 eV is obtained at the 95% confidence level.

First measurement of A N at s = 200 GeV in polarized proton–proton elastic scattering at RHIC

We report on the first measurement of the single spin analyzing power (A_N) at sqrt(s)=200GeV, obtained by the pp2pp experiment using polarized proton beams at the Relativistic Heavy Ion Collider (RHIC). Data points were measured in the four momentum transfer t range 0.01 < |t| < 0.03 (GeV/c)^2. Our result, averaged over the whole t-interval is about one standard deviation above the calculation, which uses interference between electromagnetic spin-flip amplitude and hadronic non-flip amplitude, the source of A_N. The difference could be explained by an additional contribution of a hadronic spin-flip amplitude to A_N.

A readout system utilizing the APV25 ASIC for the Forward GEM Tracker in STAR

We have developed a modular readout system for the 30,720 channel Forward GEM Tracker recently installed in the STAR Experiment at RHIC, BNL. The modular architecture is based on a passive compact PCI backplane running a custom protocol, not PCI, connecting 6 readout modules to a readout controller module. The readout modules provide all necessary functions, including isolated power supplies, to operate up to 24 APV25 chips per module with high-impedance ground isolation. The front-end boards contain a minimal set of components as they are located inside the STAR TPC inner field cage and are inaccessible except during long shutdown periods. The front-end boards connect to the readout modules with cables up to 24 m in length, carrying unbuffered analog readout signals from the APV25 as well as power, trigger, clock and control. The readout module digitizes the APV analog samples to 12 bits at 37.532 MHz, and zero suppresses and buffers the data. The readout controller distributes trigger and clock from the central trigger system, gathers the data over the backplane, and ships it to a linux PC via a 2.125 Gbps optical data link (Detector Data Link (DDL) from ALICE). The PC gathers data from multiple readout controllers and dispatches it to the STAR event builders. The readout modules, controllers, and backplanes are housed in a common crate together with the GEM HV bias power supplies.

The First Measurement of the Elastic pp‐scattering Spin Parameters at s = 200 GeV

Elastic scattering of polarized protons in the range of very small momentum transferred was studied for the first time at s = 200 GeV in the experiment pp2pp at RHIC. This article presents the single spin asymmetry AN and the double spin asymmetries ANN and ASS measured in this experiment.

First measurement of AN at in polarized proton–proton elastic scattering at RHIC

We report on the first measurement of the single spin analyzing power (A_N) at sqrt(s)=200GeV, obtained by the pp2pp experiment using polarized proton beams at the Relativistic Heavy Ion Collider (RHIC). Data points were measured in the four momentum transfer t range 0.01 < |t| < 0.03 (GeV/c)^2. Our result, averaged over the whole t-interval is about one standard deviation above the calculation, which uses interference between electromagnetic spin-flip amplitude and hadronic non-flip amplitude, the source of A_N. The difference could be explained by an additional contribution of a hadronic spin-flip amplitude to A_N.

First measurement of AN at s=200GeV in polarized proton–proton elastic scattering at RHIC

We report on the first measurement of the single spin analyzing power (A_N) at sqrt(s)=200GeV, obtained by the pp2pp experiment using polarized proton beams at the Relativistic Heavy Ion Collider (RHIC). Data points were measured in the four momentum transfer t range 0.01 < |t| < 0.03 (GeV/c)^2. Our result, averaged over the whole t-interval is about one standard deviation above the calculation, which uses interference between electromagnetic spin-flip amplitude and hadronic non-flip amplitude, the source of A_N. The difference could be explained by an additional contribution of a hadronic spin-flip amplitude to A_N.