Search NASA⌕ Search

SEARCH · Search NASA

Results for “LEAD 208 TARGET”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

Measurements of neutron capture cross section for {sup 207,208}Pb

The neutron capture cross sections for {sup 207,208}Pb have been measured in the neutron energy region from 10 to 110 keV. The γ-rays cascaded from a capture state to the ground state or low-lying states of {sup 208,209}Pb were observed for the first time, using an anti-Compton Nal(Tl) spectrometer and a TOF method. The observed discrete γ-ray energy spectra enabled us to determine neutron capture cross sections for {sup 207,208}Pb with small systematic errors, since we could distinguish γ-ray of {sup 207,208}Pb(n,γ) reactions from background γ-ray with use of the γ-ray spectra. The obtained cross sections include both contributions of resonance and direct capture components different from the previous TOF measurements.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

Elastic scattering of {sup 9}Li on {sup 208}Pb at energies around the Coulomb barrier

We have studied the dynamical effects of the halo structure of {sup 11}Li on the scattering on heavy targets at energies around the Coulomb barrier. This experiment was performed at ISAC-II at TRIUMF with a world record in production of the post-accelerated {sup 11}Li beam. As part of this study we report here on the first measurement of the elastic cross section of the core nucleus, i.e. {sup 9}Li on {sup 208}Pb, at energies around the Coulomb barrier. A preliminary optical model analysis has been performed in order to extract a global optical potential to describe the measured angular distributions.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2012

A study on the Fresnel diffraction of {sup 6}He by means of different microscopic density distributions

The elastic scattering of the halo nucleus {sup 6}He from heavy targets such as {sup 197}Au and {sup 208}Pb has been investigated in order to explain the Coulomb rainbow peak due to the Fresnel-type diffraction observed in the experimental data. In order to examine the role of nuclear potential to describe {sup 6}He + {sup 197}Au and {sup 6}He + {sup 208}Pb systems, we have used the no-core shell model, few-body and Gaussian-shaped density distributions at various energies. The microscopic real parts of the complex nuclear potential have been obtained by using the double-folding model for each of the density distribution and the phenomenological imaginary potentials have been taken as the standard Woods-Saxon shape. We have observed that fewbody and Gaussian-shaped density distributions have given standard Fresnel-type diffraction results, a classical scattering pattern with Coulomb rainbow peak whereas the nuclear potential obtained by using the no-core shell-model density distribution has provided the reduction at Fresnel peak and has given more consistent results with the experimental data.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

First Charge-Exchange Measurements with SHARAQ

The isovector spin monopole resonances (IVSMR) of the {beta}{sup +} type were observed for the first time in the {sup 208}Pb and {sup 90}Zr(t,{sup 3}He) reactions at 300 MeV/u. The experiment was performed at the RI Beam Factory (RIBF) at RIKEN by using the newly-constructed magnetic spectrometer SHARAQ. The double differential cross sections for the {sup 208}Pb and {sup 90}Zr(t,{sup 3}He) reactions were obtained at the excitation energy of 0{<=}E{sub x}{<=}70 MeV and the scattering angles of 0 deg. {<=}{theta}{<=}3 deg. The monopole component was identified by making a difference between the zero-degree and backward-angle spectra. The signatures of the IVSMR are observed at an excitation energy of 12 MeV(20 MeV) in {sup 208}Pb({sup 90}Zr)(t,{sup 3}He) reaction, which agrees fairly well with the theoretical predictions.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

Using Neutrino Nucleus Interactions as a Probe of the Strong Interaction

Neutrino scattering experiments have been studying QCD for over 30 years. From the Gargamelle experiments in the early 70's, through the subsequent bubble chamber and electronic detector experiments in the 80's and 90's, neutrino scattering experiments have steadily accumulated increasing statistics and minimized their systematic errors. An example of the more recent studies of QCD with neutrinos is from the TeVatron neutrino beam--the NuTeV {nu}-Fe experiment. The problem the community faces in trying to study QCD with modern neutrino data is that there is no experimentally verified way to scale neutrino-nucleus (for example, Fe) results to the equivalent neutrino-nucleon values making it difficult to combine neutrino nucleus scattering data with charged-lepton nucleus and nucleon scattering data in QCD global fits to extract parton distribution functions. This is particularly crucial since there is now indications that nuclear effects in neutrino nucleus interactions are different than those measured in charged-lepton nucleus scattering. To better understand this situation, the MINER{nu}A neutrino-nucleus scattering experiment at Fermilab, a collaboration of elementary-particle and nuclear physicists, is systematically studying neutrino nuclear effects off of He, C, Fe and Pb for a more thorough A-dependent study of nuclear PDFs and these correction factors.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Nuclear Physics with MINERvA

MINERvA is a precision neutrino experiment designed to improve our understanding of the neutrino-nucleus interaction. The experiment uses a fully active scintillation detector to allow full event reconstruction and includes nuclear targets helium, water, carbon, iron and lead. Here we describe the first steps in measuring lead to iron to carbon cross section ratios.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Status of the OPERA experiment

The OPERA experiment in the underground Gran Sasso Laboratory (LNGS) has been designed to perform the first detection of neutrino oscillations in direct appearance mode in the muon to tau neutrino channel. The detector is hybrid, being made of an emulsion/lead target and of electronic detectors. It is placed in the CNGS neutrino beam 733 km away from the neutrino source. Runs with CNGS neutrinos were successfully carried out from 2008 and the following years. The analysis of a sample of events corresponding to 1.89x10{sup 19} p.o.t. in the CERN CNGS {nu}{sub {mu}} beam yielded the observation of a first candidate {nu}{sub {tau}} CC interaction. The topology and kinematics of this candidate event is described in detail. The background sources are explained and the significance of the observation of the first {nu}{sub {tau}} event candidate is assessed.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Review of Activities using the Pulsed Neutron Facility and 2.5-GeV Electron Linac at Pohang Accelerator Laboratory

We report on activities using a pulsed neutron facility consisting of an electron linear accelerator, a water-cooled Ta target with a water moderator, and a 12 m time-of-flight path. It is possible to measure neutron total cross sections in the neutron energy range from 0.01 eV to a few hundred eV by using the neutron time-of-flight method; photo-neutron cross sections can also measure by using the bremsstrahlung from the electron linac. A {sup 6}LiZnS(Ag) glass scintillator was used as a neutron detector. The neutron flight path from the water-cooled Ta target to the neutron detector was 12.1 m. In this paper, we report total cross sections of Nb and also resonance parameters obtained using the SAMMY fitting program. The present results are compared with the previous experimental results and the evaluated data in ENDF/B-VII. We also report on the mass-yield distribution of fission products in the 2.5-GeV bremsstrahlung-induced fission of {sup nat}Pb and {sup 209}Bi measured at the 2.5-GeV electron linac using a recoil catcher and an off-line {gamma}-ray spectrometric technique.

43 PARTICLE ACCELERATORS↗
DOE OSTI2013

A measurement of the muon-induced neutron yield in lead at a depth of 2850 m water equivalent

We present results from the measurement of the neutron production rate in lead by high energy cosmic-ray muons at a depth of 2850 m water equivalent (mean muon energy of 260 GeV). A tonne-scale highly segmented plastic scintillator detector was utilised to detect both the energy depositions from the traversing muons as well as the delayed radiative capture signals of the induced neutrons. Complementary Monte Carlo simulations reproduce well the distributions of muons and detected muon-induced neutrons. Absolute agreement between simulation and data is of the order of 25%. By comparing the measured and simulated neutron capture rates a neutron yield in pure lead of (5.78{sub −0.28}{sup +0.21})×10{sup −3} neutrons/muon/(g/cm{sup 2}) has been obtained.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2015

Measurements of pion production in eA with the CLAS detector

Preliminary results on semi-inclusive charged pion production in eA collisions at E{sub beam}=5 GeV/c{sup 2} are presented. The data were collected using the CLAS detector, which is a multipurpose, large acceptance, magnetic spectrometer located in Hall B at the Thomas Jefferson National Accelerator Facility. Selected distributions in W, Q{sup 2}, p{sub π}, and θ{sub π} are shown for data produced using deuterium, carbon, iron and lead targets. Preliminary comparisons with data simulated using the GENIE generator are made. The motivation for this work is to provide distributions useful for tuning the hadronic final state interaction models in order to reduce uncertainties in the results extracted from current and next-generation neutrino oscillation experiments.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2012

Baryon deceleration and partonic plasma creation by strong chromofields in ultrarelativistic heavy-ion collisions

Strong chromofields generated at early stages of ultrarelativistic nuclear collisions may explain not only creation of the quark-gluon plasma but also collective deceleration of net baryons. This is demonstrated by solving classical equations of motion for baryonic slabs under the action of a time-dependent chromofield. We have studied sensitivity of the slab trajectories and their final rapidities to the initial strength and decay time of the chromofield, as well as to the back reaction of the produced plasma. By proper choice of the initial chromofield energy density we can reproduce significant baryon stopping, an average rapidity loss of about two units, observed for Au + Au collisions at RHIC. Using a Bjorken-like hydrodynamical model with the particle production source, we also study the evolution of partonic plasma produced as the result of the chromofield decay. Due to the delayed formation and expansion of plasma its maximum energy density is significantly lower than the initial energy density of the chromofield. It is shown that the fluctuations of the chromofield due to the stochastic distribution of color charges help to populate the midrapidity region in the net-baryon distribution. To fit the midrapidity data we need the chromofields with initial energy densities in the range of 30 to 60 GeV/fm{sup 3}. Predictions of baryon stopping for Pb + Pb collisions at LHC energies are made.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

The MINERνA detector

MINERνA (Main INjector Experiment for ν-A) is a dedicated neutrino-nucleus scattering experiment at Fermilab. It uses a fine-grained fully active detector to make precision measurements of neutrino and antineutrino interactions on a variety of different nuclear targets (plastic scintillator, C, Fe, Pb, He and H2O) for energies up to few GeV. An overview of the experiment and a description of the detector are presented.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

Neutral Current {nu} Induced Reactions in Nuclei at Supernova Neutrino Energies

We calculate cross sections for the neutral current induced neutrino/antineutrino reaction from {sup 208}Pb target and applied it to study Supernova neutrino event rates. The calculations are done in local density approximation taking into account Pauli blocking, Fermi motion effects and renormalization of weak transition strengths in the nuclear medium. The numerical results for the neutrino nucleus total cross sections have been averaged over the various Supernova neutrino/antineutrino fluxes available in literature.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

Measuring dynamical K/{pi} and p/{pi} fluctuations in AuAu collisions from the STAR experiment

Results from new measurements of dynamical K/{pi} and p/{pi} ratio fluctuations are presented. Dynamical fluctuations in global conserved quantities such as baryon number, strangeness, or charge may be observed near a QCD critical point. The STAR experiment has previously acquired data in AuAu collisions at the energies {radical}s{sub NN} = 200, 130, 62.4, and 19.6 GeV and CuCu collisions at {radical}s{sub NN} = 200, 62.4, and 22.4 GeV. The commencing of a QCD critical point search at RHIC has extended the reach of possible measurements of dynamical K/{pi} and p/{pi} ratio fluctuations from AuAu collisions to lower energies. New results are compared to previous measurements and to theoretical predictions from the UrQMD model.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

Searching for the QCD critical point in AA collisions at CERN SPS

We investigate the transverse momentum correlations of pairs of opposite charged pions near their production threshold. Through intermittency analysis, we search for power-law dependence on observation scale, as dictated by critical QCD. We analyze the data on the most central collisions in four A systems (A = p, C, Si, Pb) at maximum SPS energy. We find a significant effect for the SiSi system approaching in size the critical QCD predictions as measured by the intermittency index {phi}{sub 2}. Absence of this effect in the ({pi}{sup -}, {pi}{sup -}) sector of the SiSi system gives further support that the observed behavior in the isoscalar mode is of critical origin.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

Multiparticle azimuthal correlations of negative pions in nucleus-nucleus collisions

Multiparticle azimuthal correlations of {pi}{sup -} mesons have been studied in dC, HeC, CC, CNe, MgMg, (d, He)Ta, CCu, CTa, and OPb collisions at momentum of 4.2, 4.5 GeV/c per nucleon within the standard transverse momentum analysis method of P. Danielewicz and G. Odyniec. The data were obtained by SKM-200-GIBS and Propane Bubble Chamber Collaborations of JINR. The axis has been selected in the phase space and with respect to this axis {pi}{sup -} meson correlations were observed. The values of the coefficient of the correlations linearly depend on the mass numbers of projectile (A{sub P}) and target (A{sub T}) nuclei. The Quark-Gluon String Model satisfactorily describes the experimental results.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2015

Very low-energy neutrino interactions

Neutrino-nucleus reaction cross sections are now evaluated rather accurately by shell-model (SM) or SM+RPA calculations based on recent advances in nuclear structure studies. Due to these achievements, reliable constraints on super-nova neutrino temperatures as well as neutrino oscillation parameters become possible. Supernova neutrino tempeatures are constrained from abundances of elements obtained by using new ν-nucleus reaction cross sections. A possibility of constructing supernova neutrino spectrum from beta-beam measurements is pointed out. Neutrino mass hierarchy and mixing angle θ{sub 13} can be determined from abundance ratio of {sup 7}Li/{sup 11}B, which is sensitive to the MSW matter oscillation effects in supernova explosions. Inverted mass hierarchy is shown to be statistically more favored based on a recent analysis of presolar grains. Effects of neutrino-neutrino interactions are also shown to play important roles in r-process nucleosynthesis. Importance and possibilities of direct measurements of ν-induced cross sections on {sup 40}Ar and {sup 208}Pb are discussed for future supernova neutrino detections. Recent calculations of the cross sections for ν-{sup 40}Ar are presented. The need for new theoretical evaluations of the cross sections for ν-{sup 208}Pb is pointed out. Challenges to experiments on coherent elastic scattering are presented.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
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↗