119643427
Star detector overview
An introduction to the STAR detector and a brief overview of the physics goals of the experiment are presented.
16629143
K/pi Fluctuations at relativistic energies.
We report K/pi fluctuations from Au + Au collisions at sqrt[s(NN)]= 19.6, 62.4, 130, and 200 GeV using the STAR detector at the Relativistic Heavy Ion Collider. K/pi fluctuations in central collisions show little dependence on incident energy and are on the same order as those from NA49 at the Super Proton Synchrotron in central Pb + Pb collisions at sqrt[s(NN)]=12.3 and 17.3 GeV. We report results for the collision centrality dependence of K/pi fluctuations and results for charge-separated fluctuations. We observe that the K/pi fluctuations scale with the charged particle multiplicity density.
13085576
Alignment of the ALICE inner tracking system with cosmic-ray tracks
ALICE (A Large Ion Collider Experiment) is the LHC (Large Hadron Collider) experiment devoted to investigating the strongly interacting matter created in nucleus-nucleus collisions at the LHC energies. The ALICE ITS, Inner Tracking System, consists of six cylindrical layers of silicon detectors with three different technologies; in the outward direction: two layers of pixel detectors, two layers each of drift, and strip detectors. The number of parameters to be determined in the spatial alignment of the 2198 sensor modules of the ITS is about 13,000. The target alignment precision is well below 10 mu m in some cases (pixels). The sources of alignment information include survey measurements, and the reconstructed tracks from cosmic rays and from proton-proton collisions. The main track-based alignment method uses the Millepede global approach. An iterative local method was developed and used as well. We present the results obtained for the ITS alignment using about 10(5) charged tracks from cosmic rays that have been collected during summer 2008, with the ALICE solenoidal magnet switched off.
123035920
The ALICE trigger system performance for p-p and Pb-Pb collisions
The ALICE trigger system installed in the experimental cavern processes information from triggering detectors at 3 hardware levels, and is used in p-p and Pb-Pb collisions. Many automatic functions have been developed to facilitate work in the control room. The hardware is permanently monitored, and around 1200 counters, with considerable built-in redundancy, are read at regular intervals (at least once per minute). This provides relevant physics information and also verifies the consistency of the hardware operation. In order to compensate for seasonal drift, the CORDE module has been installed, which allows the LHC clock to be delayed in steps of 10 ps. This paper describes the current status of the ALICE trigger system after experience with p-p and Pb-Pb runs, the new firmware developments and the appropriate software for this electronics.
7991709
Measurement of inelastic, single- and double-diffraction cross sections in proton–proton collisions at the LHC with ALICE
Measurements of cross sections of inelastic and diffractive processes in proton–proton collisions at LHC energies were carried out with the ALICE detector. The fractions of diffractive processes in inelastic collisions were determined from a study of gaps in charged particle pseudorapidity distributions: for single diffraction (diffractive mass MX<200 GeV/c2) $\sigma_{\mathrm{SD}}/\sigma_{\mathrm {INEL}} = 0.21 \pm 0.03, 0.20^{+0.07}_{-0.08}$, and $0.20^{+0.04}_{-0.07}$, respectively at centre-of-mass energies $\sqrt{s} = 0.9, 2.76\mbox{, and }7~\mbox{TeV}$; for double diffraction (for a pseudorapidity gap Δη>3) σDD/σINEL=0.11±0.03,0.12±0.05, and $0.12^{+0.05}_{-0.04}$, respectively at $\sqrt{s} = 0.9, 2.76\mbox{, and }7~\mbox{TeV}$. To measure the inelastic cross section, beam properties were determined with van der Meer scans, and, using a simulation of diffraction adjusted to data, the following values were obtained: $\sigma_{\mathrm{INEL}} = 62.8^{+2.4}_{-4.0} (\mathrm{model}) \pm1.2 (\mathrm{lumi})$ mb at $\sqrt{s} = 2.76\ \mbox{TeV}$ and $73.2^{+2.0}_{-4.6} (\mathrm{model}) \pm2.6 (\mathrm{lumi})~\mbox{mb}$ at $\sqrt{s} = 7\ \mbox{TeV}$. The single- and double-diffractive cross sections were calculated combining relative rates of diffraction with inelastic cross sections. The results are compared to previous measurements at proton–antiproton and proton–proton colliders at lower energies, to measurements by other experiments at the LHC, and to theoretical models.
28395001
Transverse-momentum and collision-energy dependence of high-pT hadron suppression in Au+Au collisions at ultrarelativistic energies.
We report high statistics measurements of inclusive charged hadron production in Au+Au and p+p collisions at sqrt[s(NN)]=200 GeV. A large, approximately constant hadron suppression is observed in central Au+Au collisions for 5<p(T)<12 GeV/c. The collision energy dependence of the yields and the centrality and p(T) dependence of the suppression provide stringent constraints on theoretical models of suppression. Models incorporating initial-state gluon saturation or partonic energy loss in dense matter are largely consistent with observations. We observe no evidence of p(T)-dependent suppression, which may be expected from models incorporating jet attenuation in cold nuclear matter or scattering of fragmentation hadrons.
55119679
Conceptual design and infrastructure for the installation of the first AGATA sub-array at LNL
The first implementation of the AGATA spectrometer consisting of five triple germanium detector clusters has been installed at Laboratori Nazionali di Legnaro, INFN. This setup has two major goals, the first one is to validate the g-tracking concept and the second is to perform an experimental physics program using the stable beams delivered by the Tandem–PIAVE-ALPI accelerator complex. A large Contents lists available at ScienceDirect
119901530
First observation of excited states in Hg172
Excited states in the extremely neutron-deficient isotope $^{172}\mathrm{Hg}$ have been established for the first time. The $^{96}\mathrm{Ru}(^{78}\mathrm{Kr},2n)$ reaction was employed to populate excited states in $^{172}\mathrm{Hg}$ with a cross section $\ensuremath{\sigma}\ensuremath{\approx}15$ nb. The highly selective recoil-decay tagging (RDT) technique was used to obtain clean in-beam $\ensuremath{\gamma}$-ray spectra for $^{172}\mathrm{Hg}$. The yrast ground-state band has tentatively been established up to $I=6 \ensuremath{\hbar}$. The data have been interpreted within the framework of total Routhian surface and quasiparticle random phase approximation calculations.
121238231
Underground multi-muon experiment EMMA
EMMA is a new experiment designed for cosmic- ray composition studies around the knee energy operating at the shallow depth underground in the Pyh¨ asalmi mine, Fin- land. The array has sufficient coverage and resolution to de- termine the multiplicity, the lateral density distribution and the arrival direction of high-energy muons on an event by event basis. Preliminary results on the muon multiplicity ex- tracted using one detector station of the array are presented.
122206593
Observation of Octupole Structures in Radon and Radium Isotopes and Their Contrasting Behavior at High Spin
Multinucleon transfer reactions have been used, for the first time, to populate high-spin bands of alternating parity states in {sup 218,220,222}Rn and {sup 222,224,226}Ra. The behavior of the angular momentum alignment with rotational frequency for the Rn isotopes is very different when compared with Ra and Th isotopes with N{approx}134, indicating a transition from octupole vibrational to stable octupole deformation. Throughout the measured spin range the values of {vert_bar}D{sub 0}/Q{sub 0}{vert_bar} remain constant for {sup 222}Ra and {sup 226}Ra and have a very small value for {sup 224}Ra, suggesting that the charge and mass distributions are not affected appreciably by rotations. {copyright} {ital 1997} {ital The American Physical Society}
16633069
Shell-structure and pairing interaction in superheavy nuclei: rotational properties of the z=104 nucleus (256)rf.
The rotational band structure of the Z=104 nucleus (256)Rf has been observed up to a tentative spin of 20ℏ using state-of-the-art γ-ray spectroscopic techniques. This represents the first such measurement in a superheavy nucleus whose stability is entirely derived from the shell-correction energy. The observed rotational properties are compared to those of neighboring nuclei and it is shown that the kinematic and dynamic moments of inertia are sensitive to the underlying single-particle shell structure and the specific location of high-j orbitals. The moments of inertia therefore provide a sensitive test of shell structure and pairing in superheavy nuclei which is essential to ensure the validity of contemporary nuclear models in this mass region. The data obtained show that there is no deformed shell gap at Z=104, which is predicted in a number of current self-consistent mean-field models.