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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 631 records · Page 35
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Φ meson production in d+Au collisions at √s NN = 200 GeV

The PHENIX Collaboration has measured Φ meson production in d+Au collisions at √s NN =200 GeV using the dimuon and dielectron decay channels. The Φ meson is measured in the forward (backward) d-going (Au-going) direction, 1.2 < y < 2.2 (–2.2 < y < –1.2) in the transverse-momentum (p T ) range from 1–7 GeV/c and at midrapidity |y|<0.35 in the p T range below 7 GeV/c. The Φ meson invariant yields and nuclear-modification factors as a function of p T , rapidity, and centrality are reported. An enhancement of Φ meson production is observed in the Au-going direction, while suppression is seen in the d-going direction, and no modification is observed at midrapidity relative to the yield in p+p collisions scaled by the number of binary collisions. As a result, similar behavior was previously observed for inclusive charged hadrons and open heavy flavor, indicating similar cold-nuclear-matter effects.

200 GeV↗
DOE OSTI2015

Superconducting Magnets for the 12 GeV Upgrade at Jefferson Lab

Jefferson Laboratory is embarked on an energy upgrade to its flagship continuous electron beam accelerator in order to expand the scope of its research capabilities and probe further into the structure of nuclear particles. The 12 GeV upgrade includes the design, manufacture, integration, installation and commissioning of eight different superconducting magnets in three separate experimental halls. The effort involves other national laboratories, universities and industry spanning three countries. This paper will summarize the key characteristics of these magnets, ranging in size from 0.2 to 23 MJ in stored energy, and featuring many different types and configurations. The paper will also give an overview of the specific technical challenges for each magnet, and a status report on magnet manufacture and expected delivery dates. The 12GeV upgrade at J-Lab represents the largest superconducting magnet fabrication and installation program currently ongoing in the United States and this paper will present the breadth of collaborations supporting it.

12 GeV upgrade, continuous electron beam accelerat↗
DOE OSTI2011

Search for e{sup +}e{sup -} {yields} f{sub 0}(600){gamma}, f{sub 0}(980){gamma}, f{sub 0}(1350){gamma}, and f{sub 2}(1270){gamma} processes in the energy range from 1.05 to 1.38 GeV

In the energy range from 1.05 to 1.38 GeV, the upper limits for the cross sections of e{sup +}e{sup -} {yields} f{sub 0}(600){gamma}, f{sub 0}(980){gamma}, f{sub 0}(1350){gamma}, and f{sub 2}(1270){gamma} {yields} {pi}{sup 0}{pi}{sup 0}{gamma} processes have been established. Measurements are performed in accordance with the statistics gathered in experiment with a spherical neutral detector (SND) on the VEPP-2M e{sup +}e{sup -} collider. The resultant upper limits vary from 6 to 42 pb depending on the energy and the model.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Variable gamma-ray sky at 1 GeV

We search for the long-term variability of the gamma-ray sky in the energy range E > 1 GeV with 168 weeks of the gamma-ray telescope Fermi-LAT data. We perform a full sky blind search for regions with variable flux looking for deviations from uniformity. We bin the sky into 12288 pixels using the HEALPix package and use the Kolmogorov-Smirnov test to compare weekly photon counts in each pixel with the constant flux hypothesis. The weekly exposure of Fermi-LAT for each pixel is calculated with the Fermi-LAT tools. We consider flux variations in a pixel significant if the statistical probability of uniformity is less than 4 Multiplication-Sign 10{sup -6}, which corresponds to 0.05 false detections in the whole set. We identified 117 variable sources, 27 of which have not been reported variable before. The sources with previously unidentified variability contain 25 active galactic nuclei (AGN) belonging to the blazar class (11 BL Lacs and 14 FSRQs), one AGN of an uncertain type, and one pulsar PSR J0633+1746 (Geminga).

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Measurement of the deflection of cosmic-ray electrons in the energy range 75-250 GeV by the Earth's magnetic field with the PAMELA experiment

The deflection of electrons in the Earth's magnetic field in the energy range 75-250 GeV (the so-called east-west effect) has been measured with the PAMELA satellite-borne experiment. The results are presented for various L-shells. The data obtained can be used to construct mathematical models that describe the structure of the Earth's magnetic field and to refine the already existing models. These data can also be directly applied to estimate the positron fraction in cosmic-ray electron fluxes both in the PAMELA experiment and in other satellite-borne experiments.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

Study of the e{sup +}e{sup –} → π{sup +}π{sup –}π{sup 0} process in the energy range 1.05–2.00 GeV

The cross section for the e{sup +}e{sup –} → π{sup +}π{sup –}π{sup 0} process in the energy range 1.05–2.00 GeV has been measured using the data collected in the experiment with the Spherical Neutral Detector (SND) at the VEPP-2000 e{sup +}e{sup –} collider. The obtained results on the cross section are in good agreement with previous measurements by the SND at the VEPP-2M collider and BABAR, but have a better accuracy.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Rotation of a 1-GeV particle beam by a fan system of thin crystals

The deflection of a 1-GeV charged particle beam by a system formed by fan-oriented thin silicon wafers has been studied theoretically and experimentally. Software has been developed for numerical simulation of a particle beam transmission through a fan crystal system. In the U-70 experiment on a proton beam, the particles were deflected by such a system through an angle exceeding 1 mrad. Thus, a new method has been demonstrated for rotating a particle beam, which can be used for creating accelerator beams for medical purposes.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2012

Neutron production in collisions between carbon nuclei of energy 2 GeV per nucleon and carbon, aluminum, copper, cadmium, and lead nuclei

Double-differential cross sections for neutron production were measured by the time-of-flight method for the interactions between carbon nuclei of energy 2 GeV per nucleon and carbon, aluminum, copper, cadmium, and lead nuclei. These measurements were performed for angles of 30 Degree-Sign , 53 Degree-Sign , and 90 Degree-Sign in the neutron-energy range fromseveral hundred keVunits to 300MeV. The phenomenologicalmodel of four moving sources was used as a basis in analyzing experimental results and in estimating the contribution to neutron emission from various reaction stages. The temperature parameters determined from the slope of the neutron energy spectra proved to be 22 {+-} 2 MeV for a hot source (fireball) and 4.5 {+-} 0.3 MeV for the stage of thermal fragmentation of highly excited heavy nuclear residues. The relative contribution of these two sources to the total neutron yield is independent of the type of the target nucleus and is about 42%, on average.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2012

Interaction of {sup 12}C ions with nuclei of enriched tin isotopes at an energy of 2.2 GeV per nucleon

The formation cross sections for about 110 products of interaction between a {sup 12}C ion beam of energy 2.2 GeV per nucleon and tin targets from the isotopes {sup 112,118,120,124}Sn were calculated. Massyield and charge distributions were obtained for {sup 112,118,124}Sn targets. An analysis of these charge distributions reveals that the positions of their maxima, Z{sub p}, are different for targets having different nucleon compositions. The formation cross sections for neutron-rich products originating from neutron-rich targets are found to increase in all product-mass regions considered in our study. Mass distributions are compared for proton-, deuteron- and ion-nucleus reactions.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2012

Formation of close-to-target products in reactions induced by {sup 12}C ions on tin isotopes at the energy of 2.2 GeV per nucleon

Cross sections for charge-exchange reactions induced by the interaction between {sup 12}C ions of energy E{sub 12{sub C}} = 2.2 GeV per nucleon and tin targets enriched in the isotopes {sup 118,120,124}Sn were measured by the induced-activity method. The cross sections for products whose charge numbers were in excess of the target charge number (Sb and Te) were determined. The shape of the isotope distribution of Sb products was indicative of the evaporative character of neutron emission in the formation of final-state products. The dependence of cross sections for charge-exchange reactions on the nucleonic composition of the target was considered. The contribution of electromagnetic excitation to the cross section for the reaction {sup 124}Sn({sup 12}C, x){sup 124}Sn was estimated.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2012

Topological cross sections in proton-proton interactions at 50 GeV

Project Thermalization (Experiment SERP-E-190 at IHEP) is aimed to study the pp interactions at 50 GeV with large number of secondary particles. In this report the experimentally measured topological cross sections have been presented taking into account the detector response and procession effciency. These data are in good agreement with gluon dominance model. The comparison with other models is also made and shows no essential discrepancies.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

K{sup -} and p-bar spectra for AuAu collisions at {radical}s = 200 GeV from STAR, PHENIX, and BRAHMS in comparison to core-corona model predictions

Based on results obtained with event generators we have launched the core-corona model. It describes in a simplified way but quite successfully the centrality dependence of multiplicity and of identified particles observed in heavy-ion reactions at beam energies between {radical}s = 17 and 200 GeV. Also the centrality dependence of the elliptic flow, {upsilon}{sub 2}, for all charged and identified particles could be explained in this model. Here we extend this analysis and study the centrality dependence of single-particle spectra of K{sup -} and p-bar measured by the PHENIX, STAR, and BRAHMS Collaborations. We find that also for these particles the analysis of the spectra in the core-corona model suffers from differences in the data published by the different experimental groups, notably for the pp collisions. As for protons and K{sup +}, for each experience the data agree well with the prediction of the core-corona model but the values of the two necessary parameters depend on the experiments. We show as well that the average momentum as a function of the centrality depends in a very sensitive way on the particle species and may be quite different for particles which have about the same mass. Therefore the idea to interpret this centrality dependence as a consequence of a collective expansion of the system, as done in blast way fits, may be premature.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

Fluctuations of the number of neutral pions at high multiplicity in pp interactions at 50 GeV

Results obtained by measuring fluctuations of the number of neutral pions in the SERP-E-190 Experiment (Thermalization Project) upon irradiating a liquid-hydrogen target of the SVD-2 setup with a beam of 50-GeV protons are presented. A simulation of the detection of photons from the decay of neutral pions with the aid of an electromagnetic calorimeter revealed a linear relation between the number of detected photons and the mean number of neutral pions in an event. After the introduction of corrections for the loss of charged tracks because of a limited acceptance of the setup, trigger operation, and the efficiency of the data-treatment system, distributions of the number of neutral pions, N{sub 0}, were obtained for each value of the total number of particles in an event, N{sub tot} = N{sub ch} + N{sub 0}. The fluctuation parameter {omega} = D/ Left-Pointing-Angle-Bracket N{sub 0} Right-Pointing-Angle-Bracket was measured. In the region N{sub tot} > 22, fluctuations of the number of neutral pions increase, which, within statistical models (GCE, CE, MCE), indicates that the system involving a large number of pions approaches the pion-condensate state. This effect was observed for the first time.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Fission and fragmentation of {sup 208}Pb nuclei in collisions with gold nuclei at an energy of 158 GeV per nucleon

The fission and fragmentation of ultrarelativistic {sup 208}Pb nuclei in collisionswith gold nuclei were studied by using a beam from the SPS accelerator at CERN at an energy of 158 GeV per nucleon. The detectors of the target area of the NA45/CERES spectrometer were used in respective measurements. The value obtained for the fission cross section is 301 {+-} 44 mb, where about 77% of events stem from the electromagnetic interaction of colliding nuclei, while the remaining part is the contribution of peripheral nuclear interactions. The spallation of lead nuclei that involves the formation of heavy fragments occurs only in collisions where the impact parameter satisfies the condition b > 10 fm. A complete disintegration of lead nuclei to intermediate-mass fragments and light particles is observed in some peripheral collisions.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2013

Polarization effects in the quasielastic (p, 2p) reaction with the nuclear S-Shell Protons at 1 GeV

The polarization of the secondary protons in the (p, 2p) reaction with the S-shell protons of nuclei {sup 4}He, {sup 6}Li, {sup 12}C, {sup 28}Si, {sup 40}Ca was measured at 1 GeV unpolarized proton beam. The spin correlation parameters C{sub ij} for the {sup 4}He and {sup 12}C targets also were for the first time obtained as well. The polarization measurements were performed by means of a two-arm magnetic spectrometer, each arm of which was equipped with the multiwire-proportional chamber polarimeter. This experiment was aimed to study a modification of the proton-proton scattering matrix in the nuclear medium.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2013

Measurement of the yields of positively charged particles at an angle of 35 Degree-Sign in proton interactions with nuclear targets at an energy of 50 GeV

Momentum spectra of cumulative particles in the region of high transverse momenta (P{sub T}) in pA {yields} h{sup +} + X reactions were obtained for the first time. The experiment in which this was done was performed at the SPIN setup (Institute for High Energy Physics, Protvino) in a beam of 50-GeV protons interacting with C, Al, Cu, and W nuclei. Positively charged particles were detected at a laboratory angle of 35 Degree-Sign and in the transverse-momentum range between 0.6 and 3.7 GeV/c. A strong dependence of the particle-production cross section on the atomic number was observed. A comparison with the results of calculations based on the HIJING and UrQMD models was performed in the subcumulative region.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2013

Dissociation of {sup 10}C nuclei in a track nuclear emulsion at an energy of 1.2 GeV per nucleon

The charge topology in the fragmentation of {sup 10}C nuclei in a track nuclear emulsion at an energy of 1.2 GeV per nucleon is studied. In the coherent dissociation of {sup 10}C nuclei, about 82% of events are associated with the channel {sup 10}C {yields} 2{alpha}+ 2p. The angular distributions and correlations of product fragments are presented for this channel. It is found that among {sup 10}C {yields} 2{alpha}+ 2p events, about 30% are associated with the process in which dissociation through the ground state of the unstable {sup 9}Be{sub g.s.} nucleus is followed by {sup 8}Be{sub g.s.} + p decays.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2015

Measurement of the total spectrum of electrons and positrons in the energy range of 300–1500 GeV in the PAMELA experiment with the aid of a sampling calorimeter and a neutron detector

A method based on the use of a sampling calorimeter was developed for measuring the total energy spectrum of electrons and positrons from high-energy cosmic rays in the PAMELA satellite-borne experiment. This made it possible to extend the range of energies accessible to measurements by the magnetic system of the PAMELA spectrometer. Themethod involves a procedure for selecting electrons on the basis of features of a secondary-particle shower in the calorimeter. The results obtained by measuring the total spectrum of cosmic-ray electrons and positrons in the energy range of 300–1500 GeV by the method in question are presented on the basis of data accumulated over a period spanning 2006 and 2013.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗