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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 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2011

Influence of nucleus potential on kaon and antikaon pairs decayed from short lived particles in a nucleus

We propose a possible way to probe the interactions of kaon- and antikaon-nucleus by measuring K{sup +}K{sup -} pairs decayed from {phi}(1020) meson in a nuclear target. The K{sup +}K{sup -} pairs emerged from nuclei can be affected by hadronic potentials and the difference of kaon- and antikaon-nucleus potential maybe modify invariant masses of K{sup +}K{sup -} decayed from {phi} mesons. The {phi} mesons can be produced with a lead target for the energy region 1.5{approx}2.4 GeV at LEPS facility in Super Photon Ring 8-GeV (Spring-8). By comparing results of Monte Carlo calculation with experimental data, we can probe kaon-, and antikaon-nucleus potential.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2018

Fluorographite-co-polydimethylsiloxane coated polyvinylidene-fluoride membrane for desalination of highly saline water with humic acid in direct contact membrane distillation

Highlights: • Surface modifications by FGi particles with PDMS binder of PVDF microporous membranes shown improvement in DCMD. • LEP with DI water & performance of M2-M4 modified membranes in DCMD was enhanced with 1M NaCl & 10 ppm HA feed solution. • Amphiphobicity was evidenced by CA with low surface tension liquids upto 38 dyne/cm as well as with canola oil. • EDX analysis proved enhancement in FC ratio and membrane surface analysis lead to understand enhanced performance in DCMD. Membranes with amphiphobic properties are crucial for desalination of concentrated saline water with organic foulant by membrane distillation. In this research, we coated Fluorographite (FGi) particles on polyvinylidene-fluoride (PVDF) flat sheet membranes with 0.8% v/v polydimethylsiloxane (PDMS) as binder by filtration coating method. We evaluated its amphiphobicity via contact angles which were observed by DI water, canola oil and organic solutions as mimicking for oleophobicity. Surface modifications by FGi particles on the surface of membranes was introduced with PDMS binder which brought bifunctionality of amphiphobicity to enhance hydrophobicity and oleophobicity. We also investigated performance of coated membranes in direct contact membrane distillation (DCMD) with 1 molar concentrated NaCl solution along with humic acid being organic foulant and compared with virgin membrane (M1 membrane) and Liquid entry pressure (LEP) was also evaluated. LEP was measured by dynamic method which shown considerable improvement in coated membranes. M3 membrane showed overall better performance in terms of salt rejection higher than 99.87% and flux as compared to M1 membrane. Furthermore, the evaluation of surface characterizations was done by FESEM with EDX, AFM and FTIR. Surface morphology confirmed the coating of FGi on membrane surface while EDX evidenced increase in atomic percent of fluorine in turn F:C ratio.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2010

An alternative explanation for the {Theta}(1540) pentaquark peak

We have studied the {gamma}d{yields}K{sup +}K{sup -}np reaction in which the LEPS collaboration found a signal in the K{sup +}n invariant mass for the claimed {Theta}(1540) pentaquark peak. Our study reveal that the procedure used at LEPS to reconstruct the K{sup +}n invariant mass generates an artif cial strength in the {Theta}(1540) region and that the LEPS collaboration underestimated the background in that region, such that the signal observed for the {Theta}(1540) is compatible with a fluctuation of 2{sigma} over the calculated background.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Critical view of the claimed {Theta}{sup +} pentaquark

We use a theoretical model of the {gamma} d{yields}K{sup +}K{sup -}n p reaction adapted to the experiment done at LEPS where a peak was observed and associated to the {Theta}{sup +}(1540) pentaquark. The study shows that the method used in the experiment to associate momenta to the undetected proton and neutron, together with the chosen cuts, necessarily creates an artificial broad peak in the assumed K{sup +}n invariant mass in the region of the claimed {Theta}{sup +}(1540). It is shown that the LEPS fit to the data, used to make the claim of the {Theta}{sup +}(1540), grossly distorts the background. An alternative fit, assuming a background plus a fluctuation, returns a background practically equal to the theoretical one and a fluctuation identical to the one seen in the experimental K{sup -}p spectrum of 2{sigma} significance.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Study of the {gamma}d {yields} K{sup +}K{sup -}np reaction and an alternative explanation for the ''{Theta}{sup +}'' peak

We look for an explanation of the peak in the K{sup +}n invariant mass distribution of the {gamma}d {yields} K{sup +}K{sup -}n p reaction that was associated to the {Theta}{sup +}(1540) pentaquark at LEPS. For this we develop a theoretical model adapted to the experiment. The study shows that the method used in the experiment to associate momenta to the undetected proton and neutron, together with the chosen cuts, necessarily creates an artificial broad peak in the assumed K{sup +}n invariant mass in the region of the claimed {Theta}{sup +}(1540), such that the remaining strength seen for the experimental peak is compatible with a fluctuation of 2{sigma} significance.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Incoherent {phi} photo-production from deuteron in SPring-8/LEPS

We present measurements of differential cross sections and decay asymmetries of incoherent {phi}-meson photo-production from the deuteron at forward angles using linearly polarized photons beam in energy range from the production threshold to E = 2.4 GeV. The experiment was performed at the SPring-8/LEPS facility. The differential cross section of incoherent production shows a large suppression compared with the free proton case. The reduction for the deuteron cannot be clearly explained in terms of simple isospin asymmetry. The decay asymmetry of incoherent {phi} photo-production shows that the eta exchange process is small. Since the exclusive K{sup +}K{sup -}p cross section shows the same reduction with incoherent, both the proton and neutron cross section reduce similarly. Consequently, the {pi}-{eta} interference effect is small too. The present results suggest that our understanding of {phi} photo-production within a nucleus should be rearranged.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Differential cross sections and spin density matrix elements for {gamma}p {yields} {phi}p from CLAS

Preliminary differential cross-sections and the {rho}{sub MM'}{sup 0} spin density matrix elements (SDME) for the reaction {gamma}{rho} {yields} {phi}p for both charged-({phi} {yields} K{sup +}K-) and neutral-mode ({phi} {yields} K{sub L}{sup 0}K{sub S}{sup 0}) topologies obtained from CLAS are presented. Our kinematic coverage is from near production threshold ({radical}(s){approx}1.97 GeV) to ({radical}(s) 2.84 GeV), with a wide coverage in the production angle. As seen in previous LEPS results, the differential cross-sections show a localized 'bump' between ({radical}(s){approx}2 and 2.2 GeV that is not expected from a simple Pomeron exchange picture. Comparisons between the charged- and neutral-mode results and possible effects from the K{sup +}{Lambda}(1520) channel are discussed. Our SDME results confirm the well-known deviations from t-channel helicity conservation (TCHC) for Pomeron exchange, but s-channel helicity conservation (SCHC) is also seen to be broken.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

A resonance interpretation for the nonmonotonic behavior of the {phi} photoproduction cross section near threshold

We study whether the nonmonotonic behavior found in the differential cross section of the {phi}-meson photoproduction near threshold can be described by a resonance. The resonant contribution is evaluated by using an effective Lagrangian approach. We find that, with the assumption of a J{sup P} 3/2{sup -} resonance with mass of 2.10{+-}0.03 GeV and width of 0.465{+-}0.141 GeV, LEPS data can indeed be well described. The ratio of the helicity amplitudes A{sub 1/2}/A{sub 3/2} calculated from the resulting coupling constants differs in sign from that of the known D{sub 13}(2080). We further find that the addition of this postulated resonance can substantially improve the agreement between the existing theoretical predictions and the recent {omega} photoproduction data if a large value of the OZI evading parameter xOZI = 12 is assumed for the resonance.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Backward-meson photoproduction at SPring-8/LEPS

Photoproductions of {pi}{sup 0} and {eta} mesons from protons were measured at backward angles. Bump structures were observed in both reaction, and a strong angular distribution of photon asymmetries was found in {pi}{sup 0} production. These structures are discussed connecting with baryon resonances.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Fragmentation function measurements at Belle

The precision measurement of fragmentation functions is an important requirement to study the spin structure of the nucleon. Unpolarized fragmentation functions at reasonably low scale and high fractional energy are necessary to complement the measurements mostly performed at LEP in order to obtain high enough precision for measurements at semi-inclusive DIS experiments and at RHIC. Those can be obtained from the abundant data collected with the Belle detector at the e{sup +}e{sup -} collider KEKB. In addition one can cleanly measure the transversely polarized fragmentation functions such as the Collins fragmentation function and the interference fragmentation functions. Both have been obtained with great precision at Belle.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

Upgrade of the cryogenic CERN RF test facility

With the large number of superconducting radiofrequency (RF) cryomodules to be tested for the former LEP and the present LHC accelerator a RF test facility was erected early in the 1990’s in the largest cryogenic test facility at CERN located at Point 18. This facility consisted of four vertical test stands for single cavities and originally one and then two horizontal test benches for RF cryomodules operating at 4.5 K in saturated helium. CERN is presently working on the upgrade of its accelerator infrastructure, which requires new superconducting cavities operating below 2 K in saturated superfluid helium. Consequently, the RF test facility has been renewed in order to allow efficient cavity and cryomodule tests in superfluid helium and to improve its thermal performances. The new RF test facility is described and its performances are presented.

43 PARTICLE ACCELERATORS↗
DOE OSTI2015

Anomalous photon-gauge boson coupling contribution to the exclusive vector boson pair production from two photon exchange in pp collisions at 13 TeV

We study the W and Z pair production from two-photon exchange in proton-proton collisions at the LHC in order to evaluate the contributions of anomalous photon-gauge boson couplings, that simulates new particles and couplings predicted in many Standard Model (SM) extensions. The experimental results of W{sup +} W{sup −} exclusive production (pp → pW{sup +}W{sup −} p) at 7 TeV from the CMS collaboration [1] updates the experimental limits on anomalous couplings obtained at the Large Electron-Positron Collider (LEP). This motivates our present analysis hopefully anticipating the expected results using the Precision Proton Spectrometer (PPS) to be installed as part of CMS. In this work, we consider the W{sup +}W{sup −} exclusive production to present the p{sub T} distribution of the lepton pair corresponding to the SM signal with p{sub T} (e, μ) > 10 GeV. Next, we consider the photon-gauge boson anomalous couplings by calculating, from the FPMC and MadGraph event generators, the process γγ → W{sup +}W{sup −} from a model with gauge boson quartic couplings, by considering a 1 TeV scale for new physical effects. We present our results for an integrated luminosity of 5 fb{sup −1} at center-of-mass energy of 7 TeV and for an integrated luminosity of 100 fb{sup −1} at 13 TeV. We present our preliminary results for Z pair exclusive production from two-photon exchange with anomalous couplings, where the ZZγγ quartic coupling is absent in the SM. We calculate the total cross section for the exclusive process and present the four lepton invariant mass distribution. Finally we present an outlook for the present analysis.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

The γ{sup *}γ{sup *} total cross section in NLA BFKL

We study the γ{sup *}γ{sup *} total cross section in the NLA BFKL approach. We have extracted the NLO corrections to the photon impact factor from two recent papers of Balitsky and Chirilli and Chirilli and Kovchegov and used them to build several representations of the total cross section, equivalent within the NLA. We have combined these different representations with two among the most common methods for the optimization of a perturbative series, namely PMS and BLM, and compared their behavior with the energy with the only available experimental data, those from the LEP2 collider.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2013

A H I IMAGING SURVEY OF ASYMPTOTIC GIANT BRANCH STARS

We present an imaging study of a sample of eight asymptotic giant branch stars in the H I 21 cm line. Using observations from the Very Large Array, we have unambiguously detected H I emission associated with the extended circumstellar envelopes of six of the targets. The detected H I masses range from M{sub H{sub I}} Almost-Equal-To 0.015-0.055 M{sub s}un. The H I morphologies and kinematics are diverse, but in all cases appear to be significantly influenced by the interaction between the circumstellar envelope and the surrounding medium. Four stars (RX Lep, Y UMa, Y CVn, and V1942 Sgr) are surrounded by detached H I shells ranging from 0.36 to 0.76 pc across. We interpret these shells as resulting from material entrained in a stellar outflow being abruptly slowed at a termination shock where it meets the local medium. RX Lep and TX Psc, two stars with moderately high space velocities (V{sub space} > 56 km s{sup -1}), exhibit extended gaseous wakes ({approx}0.3 and 0.6 pc in the plane of the sky), trailing their motion through space. The other detected star, R Peg, displays a peculiar ''horseshoe-shaped'' H I morphology with emission extended on scales up to {approx}1.7 pc; in this case, the circumstellar debris may have been distorted by transverse flows in the local interstellar medium. We briefly discuss our new results in the context of the entire sample of evolved stars that has been imaged in H I to date.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2011

When LEP and Tevatron combined with WMAP and XENON100 shed light on the nature of dark matter

Recently, several astrophysical data or would-be signals has been observed in different dark-matter oriented experiments. In each case, one could fit the data at the price of specific nature of the coupling between the Standard Model (SM) particles and a light Dark Matter candidate: hadrophobic (INTEGRAL, PAMELA) or leptophobic (WMAP Haze, dijet anomalies of CDF, FERMI Galactic Center observation). In this work, we show that when one takes into account the more recent LEP and Tevatron analysis, a light thermal fermionic Dark Matter (∼<10 GeV) that couples to electrons is mainly ruled out if one combines the analysis with WMAP constraints. We also study the special case of scalar dark matter, using a single-photon events simulation to constrain the coupling of dark matter to electron.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2014

Loopy constraints on leptophilic dark matter and internal bremsstrahlung

A sharp and spatially extended peak in an astrophysical gamma ray spectrum would provide very strong evidence for the existence of dark matter (DM), given that there are no known astrophysical processes that could mimic such a signal. From the particle physics perspective, perhaps the simplest explanation for a gamma ray peak is internal bremsstrahlung in DM annihilation through a charged t-channel mediator η close in mass to the DM particle χ. Since DM annihilation to quarks is already tightly constrained in this scenario, we focus here on the leptophilic case. We compute the electromagnetic anapole and dipole moments that DM acquires at 1-loop, and we find an interesting enhancement of these moments if the DM particle and the mediator are close in mass. We constrain the DM anapole and dipole moments using direct detection data, and then translate these limits into bounds on the DM annihilation cross section. Our bounds are highly competitive with those from astrophysical gamma ray searches. In the second part of the paper, we derive complementary constraints on internal bremsstrahlung in DM annihilation using LEP mono-photon data, measurements of the anomalous magnetic moments of the electron and the muon, and searches for lepton flavor violation. We also comment on the impact of the internal bremsstrahlung scenario on the hyperfine splitting of true muonium.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

One-side forward-backward asymmetry at the LHC

Forward-backward asymmetry A{sub FB} is an essential observable to study the nature of coupling in the standard model and physics beyond the standard model, as shown at LEP and Tevatron. As a proton-proton collider, the LHC does not have the preferred direction contrary to her counterparts, namely, LEP and Tevatron. Therefore, A{sub FB} is not applicable at the LHC. However, for the proton the momentum of the valence quark is usually larger than that of the sea quark. Utilizing this feature we have defined a so-called one-side forward-backward asymmetry A{sub OFB} for the top quark pair production at the LHC in the previous work. In this paper we extend our studies to the charged leptons and bottom quarks as the final states. Our numerical results show that at the LHC A{sub OFB} can be utilized to study the nature of the couplings once enough events are collected.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Supersymmetric leptophilic Higgs model

In the leptophilic model, one Higgs doublet couples to quarks and another couples to leptons. We study the supersymmetric version of this model, concentrating on the tightly constrained Higgs sector, which has four doublets. Constraints from perturbativity, unitarity, and LEP bounds are considered. It is found that the lightest Higgs, h, can have a mass well below 114 GeV, and for masses below 100 GeV will have a substantially enhanced branching ratio into {tau} pairs. For this region of parameter space, traditional production mechanisms (Higgs-strahlung, W fusion, and gluon fusion) are suppressed, but it may be produced in the decay of heavier particles. The second lightest Higgs has a mass of approximately 110 GeV for virtually all of parameter space, with standard model couplings, and thus an increase of a few GeV in the current lower bound on the standard model Higgs mass would rule out the model. The two heavier Higgs are both gauge phobic, one decays almost entirely into bb and can be produced via gluon fusion while the other decays almost entirely into {tau}{sup +}{tau}{sup -} but cannot be easily produced.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗