J. Sowinski

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Papers by J. Sowinski

Colliding-beam source for polarized ions

Nuclear Instruments and Methods in Physics Research

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Gamow-Teller Strengths for Neutrino Detectors

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Performance of the laser driven polarized hydrogen source at IUCF

A laser driven source of polarized hydrogen and deuterium has been installed in the Cooler Ring a... more A laser driven source of polarized hydrogen and deuterium has been installed in the Cooler Ring at the Indiana University Cyclotron Facility. Polarized nuclei from the source are injected into a storage tube, and the resulting target has been used in a scattering experiment with 200 MeV proton beam. This paper discusses the performance of the source, including measurements of atomic fraction and electron polarization.

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Identified particle elliptic flow in Au plus Au collisions at root s(NN)=130 GeV

Physical Review Letters, 2001

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Applications of the INPOL polarimeter

The INPOL polarimeter moved from LAMPF, upgraded and placed in operation at IUCF, measures polari... more The INPOL polarimeter moved from LAMPF, upgraded and placed in operation at IUCF, measures polarization transfer parameters (D_ij) up to 200 MeV incident proton energy with an effective analyzing power (A_eff) of about 30%. Also, due to the large flight path and under good beam conditions, it can be a useful device to measure transitions to weak and difficult to

Hadronization geometry from net-charge angular correlations on momentum subspace in Au–Au collisions at

Physics Letters B, 2006

We present the first measurements of charge-dependent correlations on angular difference variable... more We present the first measurements of charge-dependent correlations on angular difference variables η 1 − η 2 (pseudorapidity) and φ 1 − φ 2 (azimuth) for primary charged hadrons with transverse momentum 0.15 p t 2 GeV/c and |η| 1.3 from Au-Au collisions at √ s NN = 130 GeV. We observe correlation structures not predicted by theory but consistent with evolution of hadron emission geometry with increasing centrality from one-dimensional fragmentation of color strings along the beam direction to an at least two-dimensional hadronization geometry along the beam and azimuth directions of a hadron-opaque bulk medium.

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The spin dependent momentum distributions of the neutron and proton in 3He

Physics Letters B, 1996

The spin asymmetries in the momentum distributions of the neutron and proton in 3He are obtained ... more The spin asymmetries in the momentum distributions of the neutron and proton in 3He are obtained from a Faddeev calculation of the ground state. Both two-and three-body configurations are found to be important. Using a PWIA model and measurements of the spin asymmetries in 3&(j?,2p) and 3s(j?',pn) quasielastic scattering at 197 MeV the asymmetries in the momentum distributions are experimentally determined. Good agreement between theory and experiment is found up to initial nucleon momenta of 300 MeV/c.

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Pion, kaon, proton and anti-proton transverse momentum distributions from and collisions at

Physics Letters B, 2005

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Polarizing a stored proton beam by spin flip?

Physics Letters B, 2009

The present thesis discusses the extraction of the electron-proton spin-flip cross-section. The e... more The present thesis discusses the extraction of the electron-proton spin-flip cross-section. The experimental setup, the data analysis and the results are pictured in detail. The proton is described by a QCD-based parton model. In leading twist three functions are needed. The quark distribution, the helicity distribution and the transversity distribution. While the first two are well-known, the transversity distribution is largely unknown. A self-sufficient measurement of the transversity is possible in double polarized proton-antiproton scattering. This rises the need of a polarized antiproton beam. So far spin filtering is the only tested method to produce a polarized proton beam, which may be capable to hold also for antiprotons. In-situ polarization build-up of a stored beam either by selective removal or by spin-flip of a spin-1 2 beam is mathematically described. A high spin-flip cross-section would create an effective method to produce a polarized antiproton beam by polarized positrons. Prompted by conflicting calculations, a measurement of the spin-flip cross-section in low-energy electron-proton scattering was carried out. This experiment uses the electron beam of the electron cooler at COSY as an electron target. The depolarization of the stored proton beam is detected. An overview of the experiment is followed by detailed descriptions of the cycle setup, of the electron target and the ANKE silicon tracking telescopes acting as a beam polarimeter. Elastic protondeuteron scattering is the anaylzing reaction. The event selection is depicted and the beam polarization is calculated. Upper limits of the two electron-proton spin-flip cross-sections σ and σ ⊥ are deduced using the likelihood method. v vi Zusammenfassung In der vorliegenden Arbeit wird die Messung und Bestimmung des Elektron-Proton Spinflip Wirkungsquerschnittes vorgestellt. Der experimentelle Aufbau, die Datenanalyse und die Ergebnisse sind im Detail beschrieben. Das Proton wird durch ein QCD-basiertes Parton Modell beschrieben. In leading twist werden drei Funktionen benötigt. Es sind die Quarkdistribution, die Helizitätsdistribution und die Transversitydistribution. Obwohl die ersten beiden präzise gemessen sind, istüber die Transversitydistribution wenig bekannt. Eine von weiteren Messungen unabhängige Bestimmung der Transversitydistribution ist in doppelpolarisierten Proton-Antiproton Streuexperimenten möglich. Daraus erwächst der Wunsch, einen polarisierten Antiprotonenstrahl zu erzeugen. Bislang ist Spinfiltern die einzige an Protonen getestete Methode, die auch für Antiproton funktionieren kann. In-situ Polarisationsaufbau eines gespeicherten Spin-1 2 Strahls durch selektiven Verlust und selektiven Spinflip wird beschrieben. Ein großer Spinflip Wirkungsquerschnitt eröffnet eine effektive Methode, einen Antiprotonenstrahl zu polarisieren. Angetrieben durch sich wiedersprechende Berechnungen, wurde eine Messung des Spinflip Wirkungsquerschnittes in niederenergetischer Eletron-Proton Streuung durchgeführt. In diesem Experiment wird der Elektronenstrahl des Elektronenkühlers an COSY als freies Elektronentarget benutzt und die Depolarisation des gespeicherten Protonen Strahls gemessen. EinemÜberblicküber dem Experiment folgt eine detailierte Beschreibung der COSY Beschleunigerzyklen, des Elektronen Targets und der Silizium Tracking Teleskope, die als Polarimeter betrieben wurden. Elastische Proton-Deuteron Streuung ist als Analysereaktion verwendet. Die Eventselektion ist beschrieben und die Polarisation des Protonenstrahls wurde berechnet. Obere Grenzen der zwei Elektron-Proton Spinflip Wirkungsquerschnitte σ und σ ⊥ konnten mittels der Likelihood-Methode bestimmt werden. vii viii

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Φ Meson Production in and Collisions at

Physics Letters B, 2005

We report the STAR measurement of varphi meson production in Au+Au and p+p collisions at sNN=200G... more We report the STAR measurement of varphi meson production in Au+Au and p+p collisions at sNN=200GeV. Using the event mixing technique, the varphi spectra and yields are obtained at mid-rapidity for five centrality bins in Au+Au collisions and for non-singly-diffractive p+p collisions. It is found that the varphi transverse momentum distributions from Au+Au collisions are better fitted with a single-exponential

A measurement of the spin correlation parameter CNN (θ) in n-p scattering at 181 MeV

Physics Letters B, 1987

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Evidence from d+Au Measurements for Final-State Suppression of High-pT Hadrons in Au+Au Collisions at RHIC

Physical Review Letters, 2003

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$Research paper thumbnail of Transverse-Momentum and Collision-Energy Dependence of High-p_{T} Hadron Suppression in Au+Au Collisions at Ultrarelativistic Energies$

Transverse-Momentum and Collision-Energy Dependence of High-p_{T} Hadron Suppression in Au+Au Collisions at Ultrarelativistic Energies

Physical Review Letters, 2003

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Azimuthal Anisotropy and Correlations at Large Transverse Momenta in p+p and Au+Au Collisions at sNN=200 GeV

Physical Review Letters, 2004

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Scaling Properties of Hyperon Production in Au+Au Collisions at sNN=200 GeV

Physical Review Letters, 2007

We present the scaling properties of Λ, Ξ, and Ω in midrapidity Au+Au collisions at the Brookhave... more

Open Charm Yields in d+Au Collisions at sNN=200 GeV

Physical Review Letters, 2005

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Azimuthal Anisotropy and Correlations in the Hard Scattering Regime at RHIC

Physical Review Letters, 2003

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Evidence for a Three-Nucleon-Force Effect in Proton-Deuteron Elastic Scattering

Physical Review Letters, 2001

Developments in spin-polarized internal targets for storage rings have permitted measurements of ... more Developments in spin-polarized internal targets for storage rings have permitted measurements of 197 MeV polarized protons scattering from vector polarized deuterons. This work presents measurements of the polarization observables A y , iT 11 , and C y,y in proton-deuteron elastic scattering. When compared to calculations with and without three-nucleon forces, the measurements indicate that three-nucleon forces make a significant contribution to the observables. This work indicates that three-body forces derived from static nuclear properties appear to be crucial to the description of dynamical properties.

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ρ0 Production and Possible Modification in Au+Au and p+p Collisions at sNN=200 GeV

Physical Review Letters, 2004

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Midrapidity Λ and Λ¯ Production in Au+Au Collisions at sNN=130 GeV

Physical Review Letters, 2002

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